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Survey of Battle Casualties, Eighth Air Force, June, July, and August 1944
Allan Palmer, M. D.
The need for information regarding causes of death in KIA (killed in action) battle casualties resulted in the organization of the Medical ORS (Operational Research Section), Professional Services Division, Office of the Chief Surgeon, ETOUSA (European Theater of Operations, U.S. Army). Maj. Allan Palmer,1 MC, was appointed chief of the section on 1 June 1944.
The purpose of the Medical ORS was to investigate battle casualties from an operational point of view in order to evaluate more accurately the wounding power of various weapons and the effectiveness of protective measures. At the start, it also seemed that information would be obtained which would be of value and interest to officers, not only in the medical but also in the other services. It was postulated that the machinery for collecting data provided adequate liaison with the various branches of the Armed Forces.
Aside from occasional accidents or special incidents (appendix G, p. 827) in the United Kingdom, which were investigated by the Medical ORS, the first operational project to be dealt with was a survey of battle casualties sustained by the heavy bombardment groups of the Eighth Air Force. The survey was carried out with the cooperation of Brig. Gen. Malcolm C. Grow, USSTAF (U.S. Strategic Air Forces) surgeon, the Eighth Air Force Operational Analysis Section, the Ordnance Department, the Royal Air Force, and the Royal Canadian Air Force. A period of 3 months was taken as the time during which the day operations of the Eighth Air Force might yield a satisfactory sample of casualty data for study. The 3 months chosen were June, July, and August 1944 (D-5 to D+86). In September 1944, additional personnel were provided by the Army Air Forces, Air Technical Service Command, for a 3-month continuation of the study which was to include examination of KIA casualties from the Ninth Air Force and Troop Carrier Command.
An ideal casualty survey would provide complete information about all battle casualties and about all individuals exposed to risk, irrespective of the
severity of injury. The points which pertain to such a survey of aircrew battle casualties follow.
1. Strength of forces engaged in operations for the survey period.-(1) Bombardment divisions and groups taking part in operations; (2) types and number of aircraft and combat personnel involved, such as "man-combat missions" carried out; and (3) hospitals serving the Eighth Air Force.
2. Losses.-(1) Aircraft and personnel about which no information could be secured because of failure to return from enemy territory; and (2) casualty data, including the causes of death and regional distribution of wounds, fractures, and amputations in the personnel killed or wounded by enemy gunfire and returned to the United Kingdom in aircraft, which could be obtained from post mortem examination of the killed, interrogation and X-ray examination of the wounded in hospital, survey of "Care of Flyer" reports and group operations at AAF (Army Air Force) stations, and identification of missiles.
3. Battle damage data pertaining to aircraft in which casualties were sustained.-This information would be of the greatest importance for the identification of the weapon causing wounds in cases where the responsible missile was not retained by the casualty. As far as protection to personnel is concerned, a knowledge of the relative frequencies of hits by enemy missiles on aircraft bearing casualties, from various directions, would enable one to place protective armor more advantageously in the aircraft or on aircrew personnel.
4. Flight formations.-The formation of heavy bombers in flight should be studied from the point of view of risk to combat crew personnel.
COLLECTION OF DATA
Strength of Forces
The 40 heavy bombardment groups of the Eighth Air Force, divided into 3 divisions, are listed in table 174.
All the groups of the 1st Division were composed of B-17 aircraft and those of the 2d Division, of B-24 aircraft. Five groups of the 3d Division (34th, 486th, 487th, 490th, and 493d) were originally composed of B-24 aircraft but were changed to B-17's on 24 August, in mid-July, on 1 August, on 18 August, and on 18 August, respectively. Thus, the 3d Division also consisted entirely of B-17 aircraft on and after 24 August. Tables 175 and 176 give a summary of Eighth Air Force heavy bomber day operations, by divisions and man-combat missions, for the 3 months' period of this survey. These data were obtained through the Office of the Surgeon, USSTAF. The total number of aircrew personnel taking part in Eighth Air Force heavy bomber day operations is given in terms of "man-combat missions," the
average crew of a B-17 being 9 and the average crew of a B-24 being 10. Thus, a total of 69,682 sorties corresponds to a total of 657,096 man-combat missions for the 3 months' period.
1Casualty data are not available.
1Casualty data are not available.
The medical installations which served the Eighth Air Force during the period, in addition to sick quarters at each AAF station, were the 1st, 7th, 65th, 91st, 97th, and 184th General Hospitals and the 49th, 121st, 136th, 231st, 280th, and 303d Station Hospitals.
Of the 69,682 sorties in which 657,096 man-combat missions were accomplished, 693 aircraft (0.99 percent) and 6,540 aircrew personnel (1.00 percent or 10.0 per 1,000) were MIA (missing in action), leaving a balance of 650,556 man-combat missions in 68,989 aircraft, from which battle casualty data were available for survey. The casualty survey study pertained specifically to battle casualties resulting from enemy gunfire, sustained by the personnel carrying out and returning from a total of 650,556 man-combat missions.
A few incidental facts were collected in relation to the 6,540 aircrew personnel MIA during the 3 months. Followup records at Eighth Air Force headquarters showed that, for the first 8 months of 1944, 2 out of 5 (40 percent) MIA personnel were possibly KIA and 3 out of 5 (60 percent) were known to be WIA (wounded in action), prisoners of war, or evaders.
By arrangements through official channels, all KIA aircrew battle casualties returning to the United Kingdom in heavy bombers, as well as all those dying in hospital within 24 hours of entry or before surgical treatment, were brought for examination to the Medical ORS laboratory, located on the grounds of the
Cambridge American Military Cemetery (fig. 274). Examinations for the missile and injuries caused by the missile were made. No search was made in any part of the body where it was obvious a missile had not penetrated. The Graves Registration Service of the Quartermaster Corps at the Cambridge American Military Cemetery was very cooperative in notifying the Medical ORS when aircrew battle casualties were received for burial, so that the bodies could be brought immediately to the laboratory for examination.
Questionnaire forms, requesting such data as the circumstances of death, combat crew position, and altitude, were completed and forwarded by the group surgeons of the AAF stations from which the KIA casualties came. Of the 110 KIA casualties for the 3 months' period, 89 (81 percent) were examined at the Medical ORS. Of the 21 not examined, 7 were casualties who died in a hospital 1 to 6 days after being wounded.
Daily admission and disposition reports were received from the 12 hospitals serving the Eighth Air Force. From these, the entries of aircrew battle casualties were noted. There were 1,007 WIA battle casualties for the 3 months' period. Since ORS consisted of only one medical officer and one enlisted man during the first 2 months of the survey, it was impossible to visit and interrogate all battle casualties in hospitals before they were discharged. However, during the third month of the survey, interrogations were accomplished with the aid of additional enlisted men, and a total of 434 (43 percent) of the WIA were seen. X-ray records of the majority of the remaining WIA casualties were examined for missile size, number, and location, and for fractures. The hospital admission and disposition reports further served the purpose of determining the time spent in hospitals by WIA casualties and their redisposition to duty, to the Zone of Interior, or to a Detachment of Patients.
Further checking of the completeness of the casualty survey was accomplished by a medical officer of ORS visiting each of the 40 heavy bomber stations. The purpose of these visits was to verify the battle casualty status of aircrew members from a perusal of "Care of Flyer" reports of those patients missed in hospitals and to obtain information on battle casualties whose injuries were so slight as not to require hospitalization. The Care of Flyer reports also provided more accurate information on the final disposition of WIA casualties and on the time lost from flying status.
Missiles were identified from British and U.S.2 ordnance publications and when necessary by consultation with a member of the Ordnance Office, USSTAF. Photographic records of missiles were made periodically by a photographer supplied by the Army Pictorial Service. It was not possible to have photographic equipment issued to the Medical ORS3 for making photographic rec-
ords of fatal wounds. The only such records available were those photographs taken at the AAF stations for the USSTAF surgeon's "Body Armor Reports." These photographs were borrowed and photostatic copies of them obtained. A 39-percent photographic coverage of KIA casualties from the 1st and 2d Divisions was achieved in this way. No photographs were available of casualties sustained by the 3d Division.
Aircraft Battle Damage
Group and squadron operations offices at each of the heavy bomber stations provided the identification number of each aircraft in which a KIA or a WIA battle casualty occurred, so that a report on the damage to the plane might be secured.
Permission was obtained from the Commanding General, Eighth Air Force, for the Medical ORS to borrow, for photostatic copying, the battle damage reports of heavy bomber aircraft in which casualties had occurred. These reports were prepared by the AAF station engineers on most damaged B-17 and B-24 aircraft and were forwarded to the Operational Research Section of the Eighth Air Force. The serial numbers of aircraft in which casualties occurred were obtained from every AAF station operations office and submitted to the Eighth Air Force Operational Research Section. Since only one copy of these battle damage reports was prepared, it was necessary to obtain, deliver for photostating, and return personally the reports at regular intervals. Battle damage reports pertaining to a total of 656 aircraft, in which there were 771 casualties, were obtained. This represents a 70-percent coverage of aircraft battle damage data associated with 70 percent of the casualties in the survey. Tables 177, 178, 179, and 180 give the number and types of the aircraft examined in this way by divisions, the cause of the damage, and the number of casualties per aircraft.
1Two of these casualties were hit with 20 mm. cannon shell fragments.
The flight formations of heavy bombers over enemy territory on missions, during which there were battle casualties, were studied. Diagrammatic flight formations were obtained from the Operations Office, Operational Research Section, Eighth Air Force. A total of 288 complete group flight formation plans of Eighth Air Force heavy bombers was available. These formations were selected on the basis that in each one there was at least one
casualty in one aircraft. Thus, the relationship between casualties and flight formations for 539 battle casualties (48 percent of the total sample) was observed.
ANALYSIS OF BATTLE CASUALTIES
During the 3 months in which this survey of battle casualties returning to the United Kingdom was conducted, there were 1,117 battle casualties of whom 110 were killed and 1,007 wounded by enemy fire. Table 181 shows their distribution between the heavy bombardment groups. This represents a casualty rate of 0.172 percent (1.72 per 1,000) in terms of man-combat missions about which casualty data were available and 0.170 percent (1.70 per 1,000) of all man-combat missions. The ratio of MIA personnel to known battle casualties is approximately 6 to 1 (5.85 percent).
These figures may be compared with those given by the Surgeon, USSTAF, in his "Annual Report of Health" for 1943-44. For 1 year ending with the first month of the present survey, the battle casualty rate for the Eighth Air Force is reported as 0.201 percent (2.01 per 1,000) of man-combat missions credited. The MIA rate for the same period was 1.95 percent (19.5 per 1,000). The ratio of MIA personnel to known battle casualties was 9.7 percent or
1Changed from B-24 aircraft to B-17 aircraft during July and August 1944.
nearly 10 to 1. Thus, the casualty rate and MIA rate for the 3 months which are the subject of this report are, respectively, 15.4 and 48.7 percent less than the corresponding figures for 1943-44.
In the present survey, the 1,117 battle casualties occurred in a total of 944 aircraft. Table 182 gives their frequency and distribution in the two types of heavy bombers. Approximately 72 percent of the casualties occurred with a distribution of one per aircraft. Multiple casualties per aircraft in the two types of heavy bombers did not differ significantly in their occurrence.
From the data in tables 176 and 182, it can be seen that the aircrew battle casualty rate is 2.10 per 1,000 man-combat missions in B-17's and 1.26 per 1,000 in B-24's. Thus, the risk of becoming a battle casualty was approximately two-thirds (67 percent) greater to B-17 personnel than it was to B-24 aircrew personnel. Since this conclusion is derived from an analysis of only those casualties who were brought back to the United Kingdom, it cannot be assumed that the real risk rates in the two types of bombers are as represented by the cited figures. If, for example, there was a higher casualty rate in missing B-24 personnel than in missing B-17 personnel, the figures could change significantly. However, with the available information, one must take account of the apparent difference which is very clearly significant. The reasons or causes for the difference merit further investigation. A fuller analysis of flak hits on aircraft in which casualties occurred appears in another chapter (p. 620).
Causes of Casualties
Table 183 gives the causes of the wounds sustained by the 1,117 casualties. Approximately 86 percent of the casualties were hit by flak fragments. Less than 4 percent were hit by shells or shell fragments fired from enemy fighter planes. Practically all of the 7.8 percent of casualties hit by secondary missiles were the result of flak hits on the aircraft. Secondary missiles include fragments of Plexiglas; pieces of dural from the skin of, or objects in, the plane; bulletproof glass; brass fittings; and parts of electrical heating and radio equipment and .50 caliber machinegun ammunition.
Two unidentified missiles causing one KIA and one WIA casualty were found to be pieces of commercially pure zinc, the origin of which was not ascertained. There were three individuals who sustained injuries during more than one mission. Two were struck by flak fragments on two different missions and one was struck by Plexiglas on one mission and by flak on another. One of the two hit twice by flak was killed as a result of the second hit.
Distribution of Casualties According to Combat Position
Table 184 shows the frequency with which aircrew personnel in different combat positions became missile casualties. In this and similar tables and figures, the positions of bombardier, togglier, and nose gunner, like those of the top turret gunner and engineer, are regarded as the same.
The high casualty rate for waist gunners was partially due to the fact that heavy bombers frequently carried two waist gunners. This practice was discontinued to a large extent, but accurate information as to the frequency with which aircrews included two waist gunners during the survey was not known.
The high casualty rates for navigators and bombardiers was to be expected from their positions in the nose of the aircraft. They lacked the protection provided by other personnel and portions of the ship's structure and by being
in the most forward compartments of the aircraft; they were exposed to the greatest density of flak. The leading edges of the wings and other parts of aircraft are known to receive a greater density of flak hits than trailing edges. The lowest incidence of casualties appears to occur in the ball turret gunner's position. This was partially due to the fact that only one of the two types of aircraft (B-17) carried a man in that combat position.
The Demarcation of Body Regions
The lack of a standardized method of demarcation of the regions of the body makes it impossible to compare accurately the distribution of wounds in any two or more collections of casualty data. Most of the available information pertains only to the wounded so that the true distribution of wounds or, more accurately, hits by bullets and fragments from high explosive shells has not been recorded. The military surgeons who cared for WIA casualties were the ones who recorded the locations of wounds. Their records have been the source of material from which casualty statistics have been compiled, and little information was obtained from their records concerning the difference between the wounds of entrance and of exit. Frequently, two or more wounds may have been produced by a single missile, but the surgeon was more concerned about the treatment of wounds than about the effectiveness of weapons or the development and use of body armor. Consequently, he usually failed to record the information which would enable those interested in body armor to compile accurate data pertaining to the regional distribution of hits and the type of causative agent.
In the Medical and Surgical History of the War of the Rebellion,4 ref-
erence is made to the relative amounts of superficial area presented by the principal divisions of the human body from Longmore.5 However, the relative percentages given for the different body regions are at variance with more recently determined measurements, particularly that for the head and neck region. Longmore's figure for the head region was 8.51 percent as compared with Burns and Zuckerman's figure of 12 percent.6 In view of the fact that all complete casualty samples studied during World War II show wounds of the head and neck to be even in excess of 12 percent, it is likely that the measurement of Burns and Zuckerman is the more accurate one.
In this survey, the lines of demarcation between the body regions (fig. 275) were uniformly adhered to in accordance with those recorded by Burns and Zuckerman. The following is quoted from the British report:
There are no agreed surface markings by which one region of the body can be definitely demarcated from another-e.g., the thorax from the neck. No absolute demarcation is possible because a line projected from the surface through the body would, in certain places, pass through two or more regions. For example a shot penetrating the body horizontally just below the ribs might easily pass both through the liver (an abdominal organ) and through the lower part of the lung (a thoracic organ). Again, shots in the buttock region could be regarded as wounds of the lower limb as well as wounds of the pelvis-if they penetrated deep enough. It was therefore necessary to define certain arbitrary lines of demarcation. The following were chosen as a fair compromise.
Head and Neck Region (Symbol H)
The demarcation of the head and neck region from the thorax presents difficulties in view of the fact that the domes of the pleurae extend an inch or so above the clavicles. A line passing transversely across the body an inch above the clavicles would, however, cut out a large part of the neck, and the part which lies below the cricoid cartilage. A compromise is suggested in a line which passes transversely one inch above the upper limit of the manubrium sterni. At the back the line chosen passes immediately below the spine of the seventh cervical vertebra (vertebra prominens). This point can easily be found as it lies immediately above the most prominent vertebra when the neck is slightly bent. In side view the lower limit of the neck is taken as a line which passes immediately above the line of the clavicle.
Chest Region (Symbol C)
The shoulders, both in front and behind, are most readily demarcated from the thorax and neck by a line which joins the upper limits of the anterior and posterior axillary folds with the point where the vertical neck joins the sloping shoulders.
The demarcation of the thoracic cage from the abdomen presents difficulties. A compromise has been effected in a simple line which approximately demarcates the lower limit of the pleural cavities. In front this line is taken as passing from the lower end of the sternum obliquely downward and laterally to the eighth intercostal space. Where this line meets the anterior end of the eighth space a horizontal line is carried directly around the body, approximately across the spine of the first lumbar vertebra, to meet the anterior end of the eighth intercostal space on the opposite side.
Consideration of the relations given in several works on surface anatomy suggests that this line, though not entirely accurate, is a fair compromise between the various statements that are made about the inferior margin of the pleural cavities.
It does not, however, clearly demarcate the thorax from the abdomen in so far as penetrating wounds of a lower part of the thoracic cage might very well enter the upper abdominal organs, and especially the liver. Furthermore, some shots through the subcostal angle might hit the posterior and inferior parts of the lungs.
Abdominal Region (Symbol A)
Lines chosen to demarcate the lower limits of the abdomen in front are those passing along the inguinal lines and meeting over the pubes. At the back the line curves from the region of the anterior superior spine, up laterally and then downward to just below the middle of the natal cleft. The latter point is approximately at the level of the ischial tuberosities.
Upper Extremity Region (Symbol U)
The lines of demarcation between the upper extremity region and head-and-neck and chest regions are as described under Chest Region.
Lower Extremity Region (Symbol L)
The lines of demarcation between the lower extremity and abdominal regions are as described under Abdominal Region. Any hit from the front or back above the level of these lines would penetrate into the lower part of the abdominal cavity. They therefore provide an adequate demarcation between the abdomen and lower limbs from these two aspects. Laterally, however, they are deficient as landmarks, since a shot could smash below their level through the hip region into the pelvis.
It should be noted again that the demarcations suggested above represent useful and practical compromises, and not absolute anatomical lines of limitation. Even were the latter definable, it is doubtful whether the results obtained would have been materially affected by their use, or indeed by any other set of practical lines of demarcation which might be suggested.
A great many difficulties were encountered in the analysis of extensive and multiple wounds, especially those observed in KIA casualties. The following criteria were adhered to closely:
1. Only wounds of entrance located in the region where missiles first struck the body were recorded as hits regardless of other regions traversed by the missile.
2. A wound or hit which appeared to be located on a line of demarcation between two regions was regarded as occurring in that region in which the missile track extended beyond the point of entry. For example, a wound at the junction of the chest and upper extremity would be a wound of the chest if the missile entered the chest or would be an upper extremity wound if it was confined to the shoulder or other part of the upper extremity.
3. Bruises and abrasions were disregarded, but all missile wounds in which the skin's surface continuity was interrupted were recorded.
4. Although it is possible for a soldier who has been killed by fragments from a bursting projectile to be struck after death by other shell fragments, an effort was made to disregard such secondary hits when it was obvious that they had occurred. For example, when there were wounds of entrance on opposite surfaces which could not have occurred from the burst of a single shell, only those hits thought to be inflicted primarily were recorded.
5. When there was doubt as to which was an entrance and which an exit wound, the choice depended arbitrarily on the missile track being directed above the horizontal plane, with the man standing erect.
6. In the case of extensive mutilating wounds of one or several regions of the body-obviously due either to very large fragments or direct hits by projectiles at the instant of or just before detonation-the location of such hits was regarded as being in the region located nearest the center of the area of mutilation.
7. When a mutilating wound involved an extremity and the area of mutilation was not continuous with the mutilation of the torso, an additional hit was recorded for the extremity, and its location was regarded as being at the most proximal level of traumatic amputation.
8. Wounds resulting from an injury in addition to wounds caused by missiles were disregarded unless they could have been the cause of death.
Regional Distribution of Wounds Due to All Missiles
A distinction is made between the regional distribution and the regional frequency of wounds. In the former, a large number of wounds, considerably in excess of the number of casualties, may be distributed over the various regions of the bodies in a sample of casualties. Percentages in the tables that pertain to the regional distribution of wounds refer to the total number of wounds. In the case of regional frequency, one is concerned only with the frequency with which the various regions of the body are wounded regardless of the number of wounds in each body region. Percentages in the tables which pertain to the regional frequency of wounds refer to the number of casualties. From such tabulations, casualties who sustained wounds in more than one region of the body must either be excluded or an additional entry made for them; that is, for those hit or wounded in more than one region (Multiple, Symbol = M). Regional frequency tabulations in this survey include an additional entry for casualties wounded in more than one region of the body.
Table 185 shows the regional distribution of all wounds due to all missiles in 1,115 aircrew battle casualties. Two casualties, not included in table 185, were known to have been killed by flak before the crashlanding of their aircraft. They were badly burned, and the location of all their wounds could not be determined.
On the basis of surface area presented by the different regions of the body, the wounds of the head and neck in all casualties (21.1 percent) are more frequent than would be expected. The projected surface area of this region is approximately 12 percent of the entire body (table 199). On the other hand, the wounds of the chest and abdomen, whose mean projected surface area is approximately 27 percent of the entire body, are far below the expected number.
This and other indications of the protective value of body armor will be discussed in the section on flak casualties (p. 570). In table 185 are included all wounds even though two or more may have been produced by a single missile following a straight path. The regional distribution of wounds or, more accurately, of hits caused by flak fragments only is given in table 200.
Regional Frequency of Wounds Due to All Missiles
Table 186 shows the regional frequency of wounds due to all missiles in 1,117 casualties. A comparison of the total percentages in tables 185 and 186 reveals the slight differences between regional distribution and regional frequency tabulations of wounds in the same complete sample of WIA and KIA casualties. If the regional frequency percentages had been calculated on the basis of casualties wounded in single regions only and if those wounded in multiple regions had been omitted from the sample, the differences in values by the two methods of presentation would have been even less significant.
On the other hand, a comparison of the values from tables 185 and 186 demonstrates the relative differences in regional distribution and regional frequency tabulations of wounds that exist when samples of casualty data are broken down into WIA only and KIA only. The differences are only very slight in the case of the wounded but are very marked and of a different order entirely in the case of the killed. The reason for these differences is that the killed were much more frequently struck in multiple regions or rather that those casualties with multiple wounds were much more apt to die. Thus, head-and-neck and multiple regions were wounded in 74.5 percent of the KIA as compared with 30.3 percent in WIA casualties.
A survey of ground force casualties at Bougainville, S.I., from 15 February to 21 April 1944 (p. 281), was the first of its kind prepared by U.S. Army medical personnel that included an evaluation of wounds in both fatal and nonfatal American battle casualties. The overall case fatality rate among the ground force casualties in this sample was approximately twice as great as in the casualties of Eighth Air Force personnel. Probably, the main reason for this difference is the speed with which the air force casualties received adequate medical care. Table 187 compares the regional frequency of wounds and the case fatality rates in the Eighth Air Force in Europe and in the ground forces at Bougainville.
The marked difference in fatality rates in wounds of the head and neck (17.6 percent for Eighth Air Force casualties as compared with 37.5 percent at Bougainville) is at least partly due to the fact that a large number of the wounds of the head in Eighth Air Force casualties were mild lacerations due to Plexiglas fragments. Casualties due to flak fragments only in the Eighth Air Force and the casualties at Bougainville are compared in table 202.
Single and Multiple Wounds
Table 188 gives the incidence of wounds occurring in one or more than one region of the body. The head and neck are regarded as one region. Wounds of both upper or both lower extremities are regarded as occurring in one region, whereas wounds in one or both upper and one or both lower extremities are regarded as occurring in two regions. Thus, 39.1 percent of the KIA casualties as compared with 12.2 percent of the WIA casualties sustained wounds in more than one region.
Fractures and Amputations
The regional distribution of fractures due to all missiles is shown in table 189. In this analysis, fractures of both bones of the leg or forearm and of any number of bones of the shoulder, hip, wrist, or ankle joints and of the hand or foot or of the cranium are regarded as single fractures when produced at the same instant by one missile. When it was apparent that one missile had produced fractures in more than one region or, for example, when one missile had made an entrance and an exit wound of the same region, such as the chest or skull, and had fractured skeletal structures at both wounds, two fractures were counted. Fractures due to all missiles occurred in 31.8 percent of the casualties (26.3 percent of the wounded and 85.3 percent of the killed). In the study of fractures, the total 1,007 WIA casualties were available for study.
1Of the total 110 KIA casualties, only 102 were available for study in
regard to fracture occurrence.
However, only 102 of the 110 KIA casualties were included in the fracture survey. This explains the variation in the figures for KIA casualties and wounds and total casualties as seen in tables 185, 189, and 190.
The relationship between wounds and fractures is given in table 190. Thus, for all wounds, the incidence of fractures was 24.8 percent. In the WIA casualties, 21.5 percent of the wounds were complicated by fractures, and in the KIA, 42.3 percent of the wounds were complicated by fractures. (Compare with table 189.)
Amputations are included as fractures in tables 189 and 190 and are shown separately in table 191. There was only one instance of a surgical amputation necessary following a soft-tissue wound. The injury was a through-and-through wound of the soft tissues anterior to the left femur, necessitating amputation of the left thigh. This amputation is not included in table 191.
1Data are for 102 of the total 110 KIA casualties.
Of the WIA battle casualties, 23 (2.3 percent) sustained traumatic amputations; 20 of these amputations were due to flak. Of the remaining three, two were due to 20 mm. shells. The missile responsible for the amputation in the third case was not discovered. Two casualties had two amputations, one of both thighs and the other of one thigh and one arm. In the KIA group, all but one arm amputation, for which a 20 mm. cannon shell was responsible, were due to flak.
Return to Duty Status of Aircrew Battle Casualties
The severity of wounds sustained by aircrew battle casualties may be evaluated on the basis of time lost from flying status. For this analysis, casualties are regarded as KIA, permanently grounded, or grounded for periods of less than 24 hours, for 1 to 7 days, for 7 to 30 days, or for 30 to 90 days. The period of observation after injury was limited to 90 days. Thus, any casualty still in hospital or who had not returned to his organization after 90 days was regarded as permanently grounded. Tables 192 through 197 show the relative severity of wounds of different regions on the basis of time lost from flying status.
By regarding KIA casualties and those permanently grounded together, it is noted that 378 (33.8 percent) of the 1,117 battle casualties were permanently lost from flying status. Of the 739 casualties who returned to air-combat duty 99 (13.4 percent) lost less than a day; 256 (34.6 percent), less than a week; and
563 (76.1 percent), less than a month from flying status. Wounds of the abdomen and of more than one body region accounted for the greatest relative loss of men from air-combat duty, the rates being 55.6 and 54.5 percent, respectively. Of those whose wounds were confined to the upper extremity, only 25.5 percent were permanently lost to air-combat duty.
1During the survey period, flak fragments were responsible for all chest wounds.
Otoscopic examination of eardrums failed to reveal any case of blast injury in any of the 434 WIA battle casualties who were interrogated. The only instances of ruptured membrana tympani in the 89 KIA casualties examined were those that were torn as a result of basal skull fractures. It is known that rupture of the eardrums occurs at very much lower blast pressure than does lung damage and the absence of the former probably precludes the occurrence of any blast injury of the lungs.
CASUALTIES DUE TO FLAK
Distribution of Flak Casualties According to Combat Position
Because of the relatively large proportion (86.2 percent) of casualties due to flak, it was thought desirable to analyze them separately. Data pertaining to protection by body armor, altitude at which injuries were sustained, time interval between injury and adequate surgical treatment, time lost from flying status, sizes of fragments causing wounds, and the relative vulnerability of different parts of the body in different aircrew combat positions, will be discussed in this section. The frequency with which aircrew personnel in different combat positions became casualties due to flak is shown in table 198.
The fact that heavy bombers occasionally carried two waist gunners probably accounts for the highest flak casualty rate for that combat position
Also, the reasons for the relatively high casualty rates for bombardiers and navigators and the low casualty rate for ball turret gunners have been discussed previously.
Projected Body Surface Area
It was to be expected and it had been observed that high explosive shell fragments hit the body more at random than the "aimed" fire of bullets. Thus, it was to be expected that an analysis of wound distribution in a complete sample of WIA and KIA casualties due only to flak fragments might best reveal information pertaining to the relative degree of protection or lack of protection to the various body regions. In order to determine the mean projected area of the body and to make a correct estimate of the proportions of its different parts, it was necessary to weight observations according to the probable frequency of different positions of the body in actual operations. Unfortunately, there was no information on which to base an estimate of the correct weighting values. An arbitrary mean figure was obtained for the present study from the three views of the standing and kneeling figures and from the photograph taken from the front of the prone position (Burns and Zuckerman). By including the two other views of the prone position, the average value derived for the size of the human target may be slightly greater than the true mean projected service position. It is hardly likely that the error is as much as 5 percent. It should be noted that variations in the weighting factor would have a far greater influence on estimates of the mean projected area of the body and its parts than would alterations in the lines of regional demarcation discussed earlier. Seven men were measured, and, in spite of the differences in their size, the measurements showed a remarkable
similarity in the proportions of the mean projected area of each part of the body. Their heights and body weights were as follows:
Table 199 gives the mean smoothed values for the actual projected surface areas in square feet and percent as determined from measurements of subjects 1, 2, 3, and 4. These percentage values may be regarded as the relative proportion of hits or wounds expected to be present in the various regions of the body in a random complete sample of casualties due only to high explosive shell fragments. Less than the expected number of wounds observed in any region would be a reflection of the protection of that region, while more than the expected number of wounds observed in any region would be due to a lack of protection to that region.
The Regional Distribution of Hits Due to Flak
Table 200 shows the location of 1,222 flak hits sustained by 961 battle casualties. Table 200 also shows the relationship between the wounds expected and the wounds observed for each of the body regions on the basis of the projected surface area of each of the regions. The lower incidence of wounds in the thoracic and abdominal regions protected by body armor is quite marked. Secondary wounds due to flak fragments traversing more than one region of the body were not counted here but were included in table 185, which lists all wounds due to all missiles. The rather noticeable decrease in the incidence of wounds of the head and neck in the flak casualties (15.6 percent) as compared with those due to all missiles (21.1 percent) was due to the frequency of Plexiglas wounds in the unprotected area of the head in bombardiers and navigators.
Surgeons' records frequently gave diagnoses of wounds of the face or head due to "Flak," when in reality interrogation of the casualties revealed that fragments of flak had penetrated Plexiglas covered areas of the noses of aircraft, dispersing myriads of Plexiglas fragments. The latter, however, seldom caused wounds of any part of the body other than the eyes, the circumorbital regions, and the neck. These wounds were usually mild and caused very little loss of time from flying status. The instances in which Plexiglas was found in other parts of the body usually occurred when fragments lodged in soft tissues after being driven ahead or along the track of the shell or other metallic fragments.
The Regional Frequency of Hits Due to Flak
Table 201 shows the regional frequency of flak hits sustained by 963 flak casualties. Again, the marked differences in the regional frequency of wounds compared with KIA casualties are shown in this table.
A comparison of fatality rates is shown in table 202. The first two columns compare the case fatality rates of wounds due to all missiles with those due to flak only in aircrew personnel. The larger percentage of fatal wounds of the head due to flak (27.4 percent as compared with 17.6 percent for all missiles) is explained by the relative mildness of Plexiglas wounds of the face which are included in the first column of the table. The lower fatality rate for flak wounds of the abdomen (26.7 percent as compared with 41.1 percent for all missiles) is explained by the severity of abdominal wounds due to missiles from enemy fighter aircraft. The third column shows the case fatality rates for ground force casualties at Bougainville. The higher case fatality rates which occurred in every region of the body in the series of Bougainville casualties must clearly be due in a large part to the fact that the wounds sustained by the ground forces concerned were more severe than the
flak injuries received by the aircrews, which are the subject of the present report. It is known too that in jungle warfare as fought at Bougainville there was a preponderance of small arms or "aimed" fire, and it is known that a bullet is relatively much more lethal than a shell fragment. Another possible reason for the difference in case fatality rates in the Ground Forces and the Air Forces may be the greater speed with which air force casualties received surgical treatment. (See appendix H, page 843, for a detailed comparison of World War II missile casualty data.)
In general, the number of wounding missiles per casualty in the Air Forces was lower than in the ground force casualties. A possible explanation may
be the proximity of ground force casualties to bursts of exploding projectiles and to a greater degree of fragmentation of mortar and artillery shells as compared with antiaircraft shells.
Altitudes at Which Casualties Sustained Wounds
The altitude at which 441 (386 WIA and 55 KIA) casualties due to flak sustained wounds was known. Table 203 shows the manner in which the casualties were distributed between the two types of heavy bombers. Approximately 70 percent of casualties due to flak in B-17's were wounded at an altitude of 24,000 feet or above, whereas 92 percent in B-24's were wounded at 23,000 feet or below. This difference in altitude may in some way account for the difference in casualty rates in the two types of aircraft.
Time Interval Between Injury and Surgical Treatment
The time interval between injury and adequate surgical treatment in hospital was recorded for 375 WIA casualties due to flak. Table 204 shows the period of time which elapsed between injury and surgical treatment for casualties in the two types of aircraft. Approximately 90 percent of all WIA battle casualties were adequately treated in hospital within 4 hours after they were wounded.
Return to Flying Status
The relative severity of wounds due to all missiles, as judged by time lost from flying status, was shown in tables 192, 193, 194, 195, 196, and 197. Table 205 shows the time lost from flying status by the 963 casualties due to flak in the two types of aircraft. Thus, 64.3 percent of all casualties due to flak were returned to flying status within 3 months after being wounded.
Relationship Between Flak Fragments and Disability
If the purpose of wounding enemy personnel is to cause military loss, then it is apparent that some means must be devised for evaluating that loss on the basis of severity of the wounds. Lamport7 has stated: "If the tactical value of causing a casualty is considered as directly proportional to the days lost from full service, an incongruous result arises with a single casualty causing
100 days lost from duty being presumably equivalent in the military sense to putting each of ten men out of action for 10 days." Lamport has developed two hypotheses which may be used to demonstrate gradation of disability produced by wounds. For both of his methods, it was necessary to choose some period of disability, in days lost from active duty, that would correspond to the total military loss of a man. By the means described in his report, he arrived at the conclusion that a wound causing a man to lose 45 days amounts to a 100 percent military loss for that man and that a wound causing 6 days' loss amounts to a 50 percent military loss. Figure 276 is the curve representing Lamport's second hypothesis and shows the relationship between days lost from active duty and the percent tactical military loss.
The severity of wounds has been evaluated in terms of military losses ranging from 1 to 100 percent, and the values for these losses have been interpolated from a table which is contained in Lamport's report and reproduced here (table 206).
1Maximal loss (L) is 100 percent for T=45 days, when T=days lost from active duty. Method II (Annuity law) L=100 - 100 x 0.5066(T) / (6).
There were 376 instances where the complete flak fragments causing the wound were recovered. Added to these were casualties with through-and through fatal wounds with either no fragment or only part of a fragment retained, fatal avulsions, amputations, and decapitations. For reasons to be given later, all of the latter fatalities were regarded as being due to fragments heavier than 20 grams. The total sample of data numbers 443 observations. These include the slightly and severely wounded, as well as those who were permanently disabled or killed. In calculating the correlation coefficient, the two variables taken into account were the days lost from flying status, inter-
polated from Lamport's table into percent military loss, and the size of the fragment in grams.
For the purpose of analysis, all casualties who were lost to flying status longer than 26 days, or who were permanently disabled or killed, were grouped together with those who lost from 27 to 45 days, or in terms of military loss, from 95 to 100 percent. The correlation coefficient for the two variables was found to be 0.288±0.047. The test of significance (t) for the coefficient was found to be 6.13 (P=less than 0.01). The mean value for military loss per casualty was 90.0 percent (which corresponds to a loss of 21 days) and the mean fragment weight was 10.07 grams. A regression equation was calculated which was found to be:
where x=percent military loss and y=fragment weight in grams. It may be observed, for example, from this equation that fragments weighing 1 gram generally may be expected to produce casualties, the average of which may be regarded as a military loss of 87 percent. From table 206, this is seen to
correspond to the loss of about 17 days. Figure 277 shows the relationship between "military loss" and fragment weight in the form of a curve plotted for the 443 observations upon which this report is based.
Despite all of the other variables that must be present, the observed correlation coefficient as calculated is statistically significant and may be regarded as real. It should be pointed out, as can be seen from the table of values for the two variables x and y, that fragments weighing more than 20 gm. produced the greatest number of permanently disabled or killed casualties. It may be assumed that fragments weighing more than 20 gm. were probably so damaging to personnel, as well as to aircraft, that they were responsible for casualties in aircraft that were shot down in enemy territory, and thus the casualties could not be included in the sample of data under survey. Otherwise, the number of observations in this group might have been greater still.
Correlation Between Wound Size and Fragment Size
It seems advisable to examine the relationship between the size of a wound and the size of the fragment causing it. It should be pointed out again that the lack of available information on the velocity of fragments prevents taking that important variable into consideration here. Accurate surface areas of wounds were not determined in most instances because of the irregular outline of the area margins. Instead, the surface area of a wound has been arbitrarily regarded as the product of two dimensions in centimeters. There were 75 instances in KIA flak casualties in which both the area of the wound of entrance and the fragment size were fairly accurately determined. In all of the observations, the flak fragments were completely retained along the wound track. The wounds ranged in size from 1 cm.2 to 50 cm.2. The flak fragments ranged from 1 to 100 gm. in weight and from 1 to 9 cm. in their greatest dimension.
Correlation coefficients were calculated to show the relationship between (1) wound size and fragment weight and (2) wound size and greatest dimension of fragment. In the case of the former, the correlation coefficient was found to be 0.49±0.12 (t=4.1; P=less than 0.01). This correlation is highly significant. The degree of correlation between the size of the wound and the greatest dimension of the flak fragment is even greater as shown by the correlation coefficient of 0.63±0.12 (t=5.3; P=less than 0.01).
A further correlation coefficient was calculated; namely, that for the area of the wound against the product of the weight and maximum dimension of fragment. Although it was found to be significant, it was less so than either of the coefficients just given.
For this purpose, 36 fatal wounds due to flak fragments were available for study. Decapitations, avulsions, and amputations, obviously due to very large flak fragments, were deleted. Of the 36 fatal wounds, 6 retained part of the fragment along the wound track. The identity of the missile causing the wound in the other cases was confirmed by the knowledge that it was flak
that had damaged the aircraft in which the casualty occurred. The range of sizes in the fatal wounds in this group was from 1 cm.2 to 108 cm.2. The mean wound size was 20 cm.2, for this sample. The difference between the means of the sizes of through-and-through wounds and the sizes of wounds with retained fragments is not statistically significant. However, if only those wounds due to retained fragments weighing less than 20 gm. (54 observations) are compared with through-and-through fatal wounds, the difference in their respective mean sizes is significant-the difference being 13.80 cm.2 (standard error±5.14). Therefore, through-and-through fatal wounds in this series of observations may be regarded generally as being caused by fragments weighing more than 20 grams.
Sizes of Fragments Causing Wounds
The sizes of flak fragments responsible for wounds were determined by weighing those recovered from the dead and estimating the weights of others from their X-ray silhouettes. In the case of the latter, the fragments were estimated in grams from their linear dimensions. A large series of X-rays of fragments of known weight were available as a standard. A total of 505 flak fragments seen in X-ray films or recovered from 438 (361 WIA and 77 KIA) casualties were available for study.
The KIA casualties from whom flak fragments were available were only those examined in the Medical ORS laboratory during the 6 months' period, June through November 1944. There were 164 bodies examined from the Eighth Air Force and Ninth Air Force and Troop Carrier Command. Of the total, 144 (87.8 percent) were flak casualties. The 81 fragments causing fatal wounds in 77 casualties represent the recovery of 54.0 percent of flak fragments causing fatal wounds. Although some flak fragments were recovered from the other KIA casualties, they were not included in this analysis because there was evidence that the fragments found were only portions of the fragments causing the fatal wounds. In several instances, fragments smaller than expected were found along a missile track having both entrance and exit wounds.
In general, it may be assumed that those fragments which were completely recovered were of lower velocity and of smaller size than those which caused fatal wounds in the remaining 67 (46.5 percent) KIA casualties, from whom none or only partial fragments were recovered. In instances where more than one fragment was found in a fatal wound with one point of entrance, it was assumed that refragmentation of the primary fragment had occurred. In nearly all such cases, the refragmented fragments could be fitted together. The weight credited for such multiple fragments was the total weight of the pieces. Fragments which caused secondary wounds in KIA casualties are included in the group of fragments causing nonfatal wounds. Table 207 shows the weight distribution of flak fragments according to nonfatal and fatal wounds.
In three KIA casualties, there were two fragments, both of which caused fatal wounds. Four fragments are credited with having caused fatal wounds,
although they were recovered from the extremities. Two of these were recovered from the knee joint of one casualty and weighed 15.29 and 6.10 gm., respectively. The other two were removed from the thighs of two casualties and weighed 12.04 and 31.74 gm., respectively. In each of these cases, the actual cause of death was attributed to hemorrhage, shock, and anoxia.
A series of flak fragments of varying sizes are seen in figure 278.
Sizes of Fragments Causing Fracture Wounds
Thirty flak fragments were recovered which had caused thirty fracture wounds of the skull. Twenty-three (77 percent) of these produced fatal wounds. The 30 fragments were distributed according to weight as shown in table 208. Again, it should be stated that many fatal skull fracture wounds were observed from which no fragments were recovered. Thus, it may be concluded that flak fragments weighing more than 5 gm. are much more likely to cause fatal penetrating wounds of the skull than fragments weighing less than 5 grams.
Fifty-six flak fragments were recovered which had caused fracture wounds of the extremities. The distribution of these fracture wounds is shown in table 209. Only complete fractures of the bones or joints listed, in which the mis-
FIGURE 278.-Primary missiles (flak). Each of these fragments caused a fatal heavy bomber aircrew casualty. They range in weight from 1 to 106 gm. Some of them are broken-off retained portions of larger fragments that produced fatal through-and-through wounds. It was observed that no flak fragment weighing less than 1 gm. had been found to produce a fatal wound and that probably no fragment weighing less than 20 gm. was capable of producing a through-and-through fatal wound.
siles were retained at the site of the fracture, were included. Thus again, in general, only fragments weighing more than 5 gm. produced fatal fracture wounds of the extremities.
1Includes 6 fatal fracture wounds; 1 of the humerus,
2 of the femur, 2 of the knee, and 1 of the tibia and/or fibula.
Flak, Mortar, and Artillery Shell Fragments
In a report by the Bombing Survey Unit on American ground force casualties sustained in the Cassino area (p. 541) are some data on the sizes of mortar and artillery shell fragments causing nonfatal wounds. The sizes of fragments causing fatal wounds were not determined. Table 210 compares the sizes and distribution of 424 flak fragments which caused nonfatal wounds in 361 aircrew casualties with 157 mortar and artillery shell fragments which caused wounds in 27 ground force casualties.
The increased average number of fragments per casualty in the ground forces (5.8 percent as compared with 1.2 percent per aircrew casualty) may be partially explained by the breakup of fragments after hitting. The lower carbon content of the steel from which mortar and artillery shells are made would account for the finer breakup and the greater irregularity in the shape of their fragments. The preponderance of wounds in ground force casualties associated with fragments smaller than 1 gm. in weight (88.5 percent as compared with 39.1 percent for aircrew casualties) attests to the greater vulnerability of ground force troops and to the greater protection of aircrew personnel against small low-velocity fragments. The casualty risk rate for troops from mortar and artillery fire in the Cassino area was estimated to be approximately 27 percent. This was the estimated casualty rate for two infantry regiments exposed to enemy mortar and artillery fire during 7 days of combat. Even with all MIA aircrew personnel included as battle casualties, the casualty rate for the Eighth Air Force for 3 months was only 1.2 percent.
The Effect of Body Armor on the Distribution of Flak Wounds
It has been impossible to collect accurate data to show the incidence of personnel hit but uninjured by flak in the regions of the body protected by armor. Records in the Office of the Surgeon, USSTAF, showed only 15 such instances for the 3 months' period of this survey. An evaluation of the protection afforded by armor may be obtained from a study of the quantitative relationship between flak hits and projected body surface areas. This relationship is shown in table 211. The values in the table are based on the 1,222 flak hits observed in the 961 casualties referred to in table 200 and may be regarded as indices of vulnerability. The mean areas of the different regions of the body used in the calculations are the same as those referred to in table 199 and are shown in table 211 as "Hits expected." The application of mean projected surface areas as measured to a man usually seated in a heavy bomber is a purely arbitrary one. The presence of combat equipment and the structure of the aircraft in addition to the wearing of body armor probably influenced the regional distribution of flak hits materially. A purely random distribution of hits on unprotected individuals would cause all the indices in the table to be 1.00. The effective protection to the chest and abdomen is apparent as indicated by indices of 0.39 and 0.22 for these regions, respectively. An index of 1.42 for the upper extremities reveals this region to be most vulnerable to hits in aircrew personnel. It should be pointed out that the relatively high vulnerability index of 1.30 for the head-and-neck region is due largely to the relatively greater vulnerability of the neck rather than of the head itself. When one compares the vulnerability of different body regions as demonstrated in table 211 with the regional distribution of hits (table 200), the point that is demonstrated in the former is the relatively high vulnerability of the head and neck and upper extremities in proportion to the surface area projected by these regions.
1Index = (Percent of hits observed) / (Percent of hits expected)
Table 212 is a breakdown of the regional distribution of flak hits given in table 200 according to combat position. The values are expressed as percentages of total hits received in each combat position.
Table 213 shows the quantitative relationship between flak hits and body surface areas in terms of vulnerability indices for each of the combat positions in U.S. heavy bomber aircraft. Here again, it may be said that a purely random distribution of hits on unprotected individuals would cause all the values in the table to be 1.00. Thus, for example, the ball turret gunner appears to have the greatest protection from flak hits of the abdomen. The copilot appears to have the least chest protection, or at least he sustains the greatest number of chest hits. However, it is clearly apparent that throughout the
different combat positions the number of flak hits of the chest and abdomen in proportion to the areas these regions present is relatively low. It is also apparent that one of the vital regions of the body, that is, the head and neck, of a man in any combat position is relatively poorly protected from flak. The head and neck are most vulnerable in the pilot's and top turret gunner's positions.
The choice of the measurements for projected surface areas was purely arbitrary and since the areas were measured for a man not in an aircraft are likely to be quite different for a man in his aircrew combat position. Perhaps a more accurate estimate of the projected surface areas of body regions for aircrew personnel and the effectiveness of body armor could be obtained from an analysis of flak wound distribution in samples of armored and unarmored aircrew personnel. The available material for such an analysis consisted of 104 of the flak casualties in the present survey (88 WIA and 16 KIA) who were known not to be wearing body armor. In addition to these, a perusal of Eighth Air Force records before the introduction of body armor revealed 307 known flak casualties (294 WIA and 13 KIA) which were sustained during the period August 1942 to December 1943.
Table 214 shows the distribution of flak wounds in unarmored and armored aircrew personnel. The figures in column 3 for armored individuals are those given in table 200 for all casualties due to flak, less those known to have been sustained in unarmored personnel.
Flak wounds of the chest and abdomen before the use of body armor accounted for 13.3 percent of the casualties as compared with 8.2 percent since the use of body armor. Chi-square test of the significance of the differences between these figures gives the value x2=9.70 (n=1, P less than 0.005). From the numbers available, this difference is very highly significant.
A number of unarmored KIA casualties were omitted from columns 1 and 2 of table 214 because the identity of the missiles causing the fatal wounds could not be ascertained from the old records. Could these have been in-
1382 WIA; 29 KIA.
cluded, the incidence of wounds of the head, chest, and abdomen undoubtedly would have been greater and the apparent beneficial effect of body armor marked. Protective steel helmets were generally worn by aircrew personnel both before and since the introduction of body armor and, as might be expected, the incidence of flak wounds of the head remained unchanged.
An analysis was made of the incidence and case fatality rates of flak injuries of the head sustained by men wearing and not wearing steel helmets. Information was obtained from 458 aircrew casualties, 369 of whom wore helmets and 89 of whom did not wear helmets (table 215). Only those regions of the head normally protected by a steel helmet were considered in this analysis.
It would appear that both the incidence and case fatality rate of injuries of the head due to flak were decreased by the wearing of the steel helmet. However, the sample of data was not sufficient to give statistical significance to the differences between either the incidence or the case fatality rate for cranial wounds of protected and unprotected individuals.
CASUALTIES DUE TO SECONDARY MISSILES
The Distribution of Casualties Due to Secondary Missiles
A total of 104 aircrew battle casualties (100 WIA and 4 KIA) were due to secondary or unknown missiles. This represents 9.3 percent of the total of 1,117 casualties in the 3 months' survey. As stated previously, secondary missiles include fragments of Plexiglas, pieces of dural from the skin of or objects in the plane, bulletproof glass, brass fittings, parts of electrical heating and radio equipment, and .50 caliber machinegun ammunition (figs. 279, 280, 281, and 282). In this analysis, however, secondary missiles left in wounds along
FIGURE 279.-Secondary missiles (dural). The most common of secondary missiles in aircrew casualties are the aluminum alloy fragments from the skin and other parts of aircraft known as dural. Only the top left fragment, the tip of the throttle of a B-17, produced a fatal wound by transecting a man's trachea and lodging in his neck alongside his vertebral column. The other pieces were found along the fatal wound tracks caused by primary missiles.
the path of enemy missiles were not included. Only those missiles which alone were responsible for wounds, secondary to hits elsewhere by flak or fire from enemy aircraft, were included. Table 216 shows the distribution of battle casualties due to secondary and unknown missiles.
All of the WIA casualties due only to Plexiglas sustained injuries from fragments of Plexiglas set in motion by flak. In one instance, a fragment of a 20 mm. cannon shell, in addition to a fracture wound of the right arm, caused
FIGURE 280.-Secondary missiles (body armor). The second most common of secondary missiles found in the tracks of fatal wounds in aircrew personnel are plates and fragments of body armor and helmet. These are most readily recognized by their uniform thickness of approximately 1 millimeter and by the fact that they are nonmagnetic though obviously of greater density than fragments of dural.
a secondary Plexiglas wound of the face. In 73 of the casualties, the wounds produced by the fragments of Plexiglas were the only ones sustained, and all of these occurred in the unprotected area of the face and neck with the exception of one, which was in the forearm. Two others sustained two wounds from Plexiglas fragments, one each of the head and forearm. Out of the total of 88 Plexiglas wounds in 76 individuals, there were only 3 that occurred on protected parts of the body; that is, parts of the body protected by as little as the sleeves of the man's uniform. These three wounds occurred on the forearms of three individuals. Figure 283 shows diagrammatically the loca-
tion of the 85 (97 percent) Plexiglas wounds that occurred on the unprotected part of the body. Plexiglas wounds were sustained by men in all combat positions. However, bombardiers, navigators, and top turret gunners accounted for 68 percent of them.
FIGURE 281.-Secondary missiles (Plexiglas). The third most common of secondary missiles causing wounds in aircrew personnel are fragments of Plexiglas. These fragments do not produce fatal wounds and never penetrate deeply into tissue except when driven in by a heavier primary missile. Plexiglas fragments produce only slight superficial wounds and lacerations by themselves.
FIGURE 282.-Secondary missiles (miscellaneous). These consist of a bearing from an aircraft's engine, parts of electrical apparatus, clothing, personal equipment, oxygen line, rubber, zipper, and "dog tag" chain. With the exception of the bearing which by itself produced a fatal head wound, all of these were found in aircrew personnel along the fatal wound tracks caused by primary missiles.
Return to Flying Status of Casualties Caused by Secondary Missiles
Table 217 shows the relative severity of wounds due to Plexiglas and other secondary and unknown missiles as judged by the time lost from flying status.
There is a striking difference in the severity of wounds due to Plexiglas fragments as compared with wounds due to flak and other missiles. Thus,
none were killed and only 8 percent of men wounded by fragments of Plexiglas were permanently grounded, whereas 43 percent of men wounded by flak or other missiles were permanently grounded or killed.
CASUALTIES DUE TO MISSILES FROM ENEMY FIGHTER AIRCRAFT
Causes of Casualties
In the present survey, 50 battle casualties (4.5 percent) were known to be due to missiles fired from enemy aircraft. Their distribution according to missile (figs. 284, 285, and 286) and type of casualty is shown in table 218. Cannon shells (20 mm.) accounted for 88 percent of the casualties.
FIGURE 284.-Primary missiles (7.92 mm.). The top specimen is the steel core of an armor-piercing 7.92 mm. Mauser bullet. The fragments in the bottom group are from the jacket of the same type of bullet.
FIGURE 285.-Primary missiles (13 mm.). Each fragment or group of fragments was found in fatal wounds of aircrew personnel. The two on the left are from armor-piercing and the two on the right are from high explosive shells. The 13 mm. cannon shell was the smallest caliber missile in which a high explosive charge was used.
Distribution of Casualties According to Combat Position
Table 219 shows the distribution of the 50 casualties according to combat position. Although the number of casualties is quite small, it may be noted that, as in the case of casualties due to flak, the waist gunner appears to be the man most vulnerable to fighter attack. This is at least partially accounted for by the fact that two waist gunners were frequently carried in heavy bombers. The tail gunner is probably most vulnerable to fighter attack. This is in agreement with the findings of the Eighth Air Force Operational Research Section that the greatest directional density of hits on heavy bombers by enemy cannon and machineguns is from dead astern.
FIGURE 286.-Primary missiles (20 mm.). Each fragment or group of fragments caused, and was found in, a fatal wound of aircrew personnel. All except the bottom group were from high explosive shells. The bottom specimen has been reconstructed from the retained fragments found in a through-and-through fatal wound produced by a 20 mm. armor-piercing incendiary cannon shell. The shell broke up in the wound as the result of its having perforated a flak suit worn by the casualty. Plates and fragments of the man's body armor were also found in the wound.
It is apparent from the distribution of casualties in table 219 that bombardiers and navigators were least likely to be casualties from enemy fighter attack. This might be expected on the basis that enemy fighters are least likely to attack the nose of an aircraft from the front. The low incidence of casualties due to missiles from fighter aircraft as compared with the high incidence due to flak for the bombardier and navigator positions substantiates the finding that these positions are susceptible to an increased density of flak hits because of their leading and exposed positions with respect to the rest of the aircraft.
Regional Distribution of Wounds Due to Missiles From Enemy Fighter Aircraft
Tab1e 220 shows the distribution of 83 wounds in 50 casualties struck by missiles fired from enemy fighter aircraft. The wound distribution in this
group of casualties differs from that in flak and other missile casualties in that there is an increase in the occurrence of wounds of the vital regions of the body. Less than 25 percent of flak wounds occurred in the head and trunk regions as compared with an incidence of 35 percent for head and trunk wounds due to missiles from enemy fighter aircraft.
Single and Multiple Wounds Due to Missiles From Enemy Fighter Aircraft
Table 221 shows the frequency with which one and more than one region of the body was wounded by missiles fired from enemy fighter aircraft in the 50 casualties. The increased multiplicity and severity of wounds in this group of casualties may be compared with those sustained by casualties due to all missiles (table 186) and flak casualties (table 201). In both of the latter, only 15
percent were wounded in more than one region as compared with 42 percent of casualties wounded in more than one region due to missiles from enemy fighter aircraft.
Altitude at Which Casualties Sustained Wounds
The altitude at which 27 of the 50 (54 percent) casualties sustained wounds was known. Table 222 shows distribution of the casualties and the type of aircraft in which they were wounded.
There are no significant variations in the distribution of B-17 casualties according to altitude. Of 5 B-24 casualties, 4 were wounded or killed below 22,000 feet. This is in agreement with the observations made pertaining to the altitude at which casualties due to flak were sustained; namely, that B-24 aircraft usually operated at a lower altitude than B-17 aircraft.
The difference in the occurrence of casualties in the two types of aircraft is marked (76 percent in B-17's and 24 percent in B-24's). However, the frequency with which B-17's and B-24's were attacked by enemy fighter aircraft is not known. Thus, the relationship between fighter damage to aircraft and the occurrence of casualties was not determined, and an evaluation of the significance of the difference in the occurrence of casualties in the two types of aircraft could not be made.
KIA CASUALTIES-JUNE THROUGH NOVEMBER 1944
During the 6 months from June through November 1944, the bodies of 164 KIA battle casualties from the Eighth Air Force and Ninth Air Force and Troop Carrier Command were examined in the laboratory of the Medical ORS.
During the last 2½ months of the survey period, the Office of the Surgeon, USSTAF, provided additional facilities and personnel to aid the ORS in the examinations.8
Causes of the Fatalities
The missiles causing fatal wounds in 164 casualties are shown in table 223. The proportion of fatalities due to flak (87.8 percent) is approximately the same as the incidence of all aircrew battle casualties due to flak (86.2 percent).
1Of these, 8 casualties were due to 20 mm. missiles and 1 each to 13 mm. and 7.92 mm. missiles.
Distribution of KIA Casualties According to Combat Position
Table 224 shows the distribution of 164 KIA casualties according to combat position. The positions of KIA casualties of the Ninth Air Force and Troop Carrier Command not accounted for in heavy bombers are included under "Position unknown." The occurrence of fatal casualties and thus the case fatality rates for casualties in any combat position do not appear to differ significantly except as previously noted in table 184.
Regional Distribution of Wounds
Table 225 shows the regional distribution of all entrance wounds due to all missiles in this larger sample of 164 KIA battle casualties. The distribution of wounds in the different body regions is not appreciably different from that of the smaller sample of 110 KIA casualties described previously in table 185.
Regional Frequency of Wounds
Table 226 shows the regional frequency of wounds in the larger sample of KIA casualties.
Comparison of tables 225 and 226 reveals again that the differences in the regional incidence of wounds by the two methods of tabulation, that is, wounds versus casualties, are quite marked. These differences are characteristic of all samples of KIA casualties and as stated before are due primarily to the high incidence of multiple wounds in the dead.
Single and Multiple Wounds
Table 227 shows the incidence of single and multiple wounds in KIA casualties. The KIA casualties were struck in more than one region four times as often as the WIA casualties. In the 3 months' survey of all casualties as discussed earlier in this chapter, multiple wounds were more than three times as frequent in KIA as in WIA casualties (39.0 percent in the KIA as compared with 12.2 percent in the WIA). The incidence of multiple regions wounded in this larger sample of KIA casualties (includes 89 of the 110 KIA from the smaller sample) was 50.0 percent. The increased number of multiple wounds in the larger sample was most marked in about half of the sample; that is, those casualties sustained during September, October, and November 1944. Such a significant increase, which would be even more marked if the incidence of multiple wounds for the first 3 months were to be compared separately with that for the second 3 months, may be regarded as being due to the increased use of higher burst velocity shells by the enemy.
Incidence of Fractures in KIA Casualties
Table 228 shows the distribution of 265 fractures according to body regions. Of the fractures in KIA casualties, 72.9 percent were associated with wounds of the vital areas of the head and trunk regions as compared with 14.3 percent in WIA casualties (table 189).
The 91 percent incidence of fractures in KIA casualties (in 149 of the 164) reported here as compared with 85.3 percent reported for the smaller sample (87 of the 102) may be explained by the increased multiplicity of wounds in the larger sample.
Causes of Death in KIA Battle Casualties Due to All Missiles
Table 229 shows the regional distribution of wounds which were the causes of death in 164 KIA casualties. There were 11 casualties in which either of 2 hits could have been fatal and 2 casualties in which any 1 of 3 hits could have been fatal. However, for this tabulation, the following criteria were followed in order to determine the primary fatal wound:
1. Only the severest one of multiple fatal wounds was regarded as the cause of death in any one casualty.
2. When the severity of a head and a chest or abdominal wound appeared to be the same, the cause of death was arbitrarily attributed to the head wound.
3. When the severity of a chest and an abdominal wound appeared to be the same, the cause of death was attributed to the chest wound.
4. Decapitations were regarded as causes of death due to wounds in the head-and-neck region in cases where the head was missing as well as in other cases where a head wound was very extensive and associated with complete evulsion of the brain.
5. In the case of extensive mutilating wounds, the cause of death was attributed to a wound of the region of the body nearest the center of the area of mutilation.
Table 230 gives the breakdown of cause of death data. Figures 287, 288, 289, 290, 291, and 292 depict typical examples of fatal wounds in aircrew casualties.
SUMMARY AND CONCLUSIONS
The survey of aircrew casualties presented here covers a period of 3 months of operational missions carried out by heavy bombers of the Eighth Air Force (D-5 to D+86). A survey of KIA casualties was continued for a further 3 months and was extended to include casualties from the Ninth Air Force and Troop Carrier Command. A total of 69,682 heavy bomber sorties (39,724 by B-17's and 29,958 by B-24's) was credited during the 3 months' period. This represents 657,096 man-combat missions completed of which 357,516 were in B-17's and 299,580 were in B-24's. During the period, 693 heavy bombers (390 B-17's and 303 B-24's) were reported "Missing-in-Action." Thus, casualty data pertaining to 6,540 (1.00 percent)
FIGURE 288.-Waist gunner in B-17 aircraft. Example of through-and-through fatal wound produced by high-velocity flak fragment. A. Wound of entrance, right (4 x 4 cm.), and wound of exit, left (4 x 7 cm.). B. Missile track laid open showing extensive mutilation of thoracic cage. C. Thoracic viscera showing widespread damage to lungs and posterior mediastinum.
FIGURE 289.-Radio operator in B-17 aircraft. Example of a fatal wound of the unprotected flank and extending into the chest, produced by a large low-velocity flak fragment. A. Entrance wound 5.5 x 14.7 cm. B. Damage to abdominal organs. C. Extensive laceration of heart with missile in situ. D. Flak fragment 83.66 grams.
officers and enlisted men were not available. Casualty data were available and studied on the 99 percent of aircraft and personnel that successfully completed and returned from 68,989 sorties or 650,556 man-combat-missions. There were 1,117 known battle casualties sustained by the Eighth Air Force during the 3 months of the survey of whom 110 had been killed and 1,007 wounded as a result of enemy gunfire. The 1,117 casualties represent an overall casualty rate of 0.172 percent (1.72 percent per 1,000 man-combat missions completed). When distributed according to types of aircraft, the casualty rates in B-17's and B-24's were 2.10 and 1.26 per 1,000 man-combat missions, respectively. The case fatality rate was 9.8 percent and did net differ significantly for casualties in the two types of aircraft.
The ratio of MIA personnel to known casualties was approximately 6 to 1. The data pertaining to casualties among MIA personnel, could they have been included in the study, might have materially influenced the observations that have been made. Of aircrew personnel, 1 percent (10.1 per 1,000 mancombat missions) were known to be missing in action. The incidence of MIA
FIGURE 290.-Navigator in B-17 aircraft. Example of fatal cranial wound due to unexploded 88 mm. higher explosive antiaircraft shell. A. Entrance hole in the nose of a B-17 aircraft of an unexploded 88 mm. high explosive antiaircraft shell. B. Fatal wound of the head produced by unexploded 88 mm. shell as it passed through the nose of a B-17 aircraft.
aircraft and personnel for the two types of bombers did not differ significantly.
Flak fragments caused 86.2 percent of the casualties. Since 7.8 percent of the casualties were due to secondary missiles, that is, those set in motion usually by flak, 94 percent of all the casualties studied may be regarded as being due to flak. Of the total casualties, 4.5 percent were caused by missiles from enemy fighter aircraft and the remaining 1.5 percent were caused by unidentified missiles.
The incidence of multiple wounds in KIA casualties during the first 3 months of the survey was 39.1 percent. This incidence increased to 50.0 percent when the KIA casualties examined during the second 3 months were included in an analysis of all KIA casualties. The increase in the multiplicity
of wounds may be regarded as evidence of an increase in the use of higher burst velocity shells by the enemy. Further evidence of this is given when a comparison is made of the incidence of fractures in the two samples of KIA casualties. During the first 3 months, the incidence of fractures was 85.3 percent, whereas for the 6 months the incidence of fractures increased to 91 percent.
The severity of wounds sustained by aircrew battle casualties was evaluated on the basis of time lost from flying status. The period of observation after injury was limited to 90 days. Of the total number of casualties (including the KIA), 33.8 percent were permanently lost from flying status. Of the WIA casualties, 9.8 percent lost a day or less from flying status, 25.4 percent
FIGURE 292.-Pilot of B-24 aircraft. A. Wound of entrance 8.4 x 13.2 cm. B. Multiple wounds of exit. C. Partial reconstruction of a 20 mm. armor-piercing incendiary cannon shell from retained fragments, 75.46 gm. D. Pieces of body armor and other personal equipment in fatal wound.
lost a week or less, 55.9 percent lost a month or less, and 17.5 percent lost from 1 to 3 months.
Approximately 70 percent of the casualties in B-17's occurred at an altitude of 24,000 feet or above, whereas 92 percent in B-24's occurred at 23,000 feet or below.
Of all WIA aircrew battle casualties, 90 percent received adequate surgical treatment in hospitals within 4 hours after they were wounded.
Since by far the majority of casualties was caused by flak, an independent analysis of all flak casualties was made. Their distribution according to combat position is shown in the order of frequency (table 231). Heavy bomber aircraft formerly carried two waist gunners, which probably accounts for the highest incidence of casualties in that combat position. The lowest incidence of casualties in the ball turret gunner's position is at least partially due to the fact that only B-17 aircraft carry a ball turret gunner.
No fragments smaller than 1 gm. were recovered from fatal wounds due to flak in KIA casualties; 92.6 percent of those recovered weighed 5 gm. or more. In WIA casualties, 39.1 percent of the fragments weighed less than 1 gram.
Plexiglas fragments set in motion by other missiles produced 88 wounds; of these 85 were on the exposed regions of the face and neck and 3 were on the forearms. There were no Plexiglas wound fatalities. Of those wounded by Plexiglas fragments, 92 percent were returned to flying duty within 90 days. It would appear that protection of the eyes and circumorbital regions with any relatively thin, shatterproof, transparent material would probably have eliminated most casualties due to Plexiglas fragments.
Of the casualties due to missiles from fighter aircraft, 88 percent were produced by 20 mm. shells. The tail gunner was found to be the most vulnerable combat position, while bombardier and navigator were the least vulnerable to enemy fighter aircraft. This is the reverse of the relative vulnerability of the same combat positions to flak and is in accordance with the findings of the Operational Research Section, Eighth Air Force, that enemy fighter aircraft usually attack heavy bombers from the rear.
A comparison is made of the regional distribution of wounds in flak casualties with and without protective body armor. From table 232, it may be seen that the incidence of flak wounds of the trunk has fallen from 13.3 percent in unarmored casualties to 8.2 percent (38 percent decrease) in casualties wearing body armor. It is apparent that the thoracic and abdominal regions have been protected by the wearing of body armor. It has been observed that the neck and axillary regions are the most highly vulnerable to penetration by enemy missiles on men wearing body armor.
The separation of casualties into "unarmored" and "armored" in table 232 does not hold so far as the occurrence of wounds of the head is concerned. Data pertaining to the protective value of head armor (steel helmet) were not sufficient to evaluate statistically.