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The death of the Red Baron 99 years ago.....

The Death of Manfred von Richthofen:
Who fired the fatal shot?


by Dr M. Geoffrey Miller
First published in "Sabretache", the Journal and Proceedings of the Military History Society of Australia, Vol. XXXIX, No. 2, June 1998, and © 1998, M. Geoffrey Miller

It is now eighty years since Baron Manfred von Richthofen, Germany’s greatest WW1 fighter pilot, was shot down and killed over the Australian lines in the Western Front in France on 21 April 1918.
Captain Brown, a Canadian pilot in the Royal Flying Corps, flying a Sopwith Camel single seat fighter, was known to have attacked von Richthofen and he was officially credited with shooting him down, eventually receiving a bar to his DSC for the feat. Brown’s claim to have shot down von Richthofen was immediately contested by the Australians because von Richthofen had flown at a very low height directly over their lines and had been fired on by Australian anti-aircraft machine gunners, as well as by many Australian soldiers.

The controversy as to who was responsible for shooting down von Richthofen has continued over the years. C E W Bean, the author of the Official History of Australia in the War of 1914 to 1918, carried out considerable research into the death and devoted an Appendix, in Volume V of the Official History, published in 1935, to describe the circumstances in detail (1). Bean was of the opinion that Sergeant Popkin, an Australian Vickers machine gunner, was responsible for shooting down von Richthofen and that Captain Brown had not fired the fatal shot.

There have been many books and articles published since then on the subject of who was responsible for shooting down von Richthofen. Most authors agree that it was an Australian, but disagree as to his identity, however Markham, (2) as late as 1993, did not consider that any Australian was responsible and wrote an article re-attributing the death of von Richthofen to Captain Brown.

This present paper will refer in particular to two books. DaleTitler (3) published a book agreeing that Australian machine gunners were responsible but considered that Gunner Robert Buie, firing a Lewis gun, shot down the German triplane. Carisella and Ryan (4) disagreed with Titler, and supported Bean’s opinion that it was Sergeant Popkin who was responsible.

Although the various authors have drawn different conclusions about who was responsible for Richthofen’s death, it is apparent that all previous accounts of the postmortem examinations made on Manfred von Richthofen have been taken from Bean’s account in Volume V of his Official History. It must be emphasised that Bean did not quote the reports in their entirety but left out some of the original text of the reports. The original complete reports are in the Richthofen section of the Bean Papers (the Bean Papers) held in the research section of the Australian War Memorial (AWM) in Canberra (5) and a consideration of these throws important new light on the controversy. There is also an unpublished letter from Popkin to Bean in the papers, clarifying an original newspaper report about Popkin that has been used by Titler and Carisella and Ryan in their books and by Markham in his article.

Using these primary sources in the Australian War Memorial, wherever possible, a critical analysis of the postmortem examination and a reconstruction of the probable events of 21 April 1918 has been made.

The Postmortem Examination
The details of the postmortem examinations of von Richthofen’s body are more than a little confused. Referring to the contradictory medical examinations made on the body of von Richthofen, Newton (6), in 1986, wrote:
The different conclusions reached in the two medical reports were to start a controversy which, to date, has never been unquestionably resolved. Who fired the fatal shot? Did it come from the air or the ground?
However a careful assessment of the documents in the Bean Papers seems to clarify the confusion.
It is accepted that Manfred von Richthofen was flying an all red Fokker triplane when he crashed in the Somme Valley near Corbie on the 21 April 1918. His body was taken to a hangar belonging to the No. 3 Squadron, Australian Flying Corps at Poulainville, where an examination of the body was held. The body was washed by an orderly and the first superficial postmortem examination was made by a panel of doctors. According to Bean (7), the panel consisted of Colonel T Sinclair, consulting surgeon to the Fourth army, Captain G C Graham, RAMC and Lieutenant G E Downs, RAMC, attached to the Air Force. Newton, however, refers to the presence also of Colonel J A Dixon, consulting physician to the British Fourth Army.

Colonel Sinclair’s report is in the Richthofen file of the Bean papers at the AWM and is as follows:
Copy extract from A.H.File No. 21/13/506
In the Field
22nd April 1918
We have made a surface examination of Captain Baron von Richthofen and find that there are only the entrance and exit wounds of one rifle bullet on the trunk. The entrance wound is on the right side about the level of the ninth-rib, which is fractured, just in front of the posterior axillary line. The bullet appears to have passed obliquely backwards through the chest striking the spinal column , from which it glanced in a forward direction and issued on the left side of the chest, at a level about two inches higher than its entrance on the right and about in the anterior axillary line.
There was also a compound fracture of the lower jaw on the left side, apparently not caused by a missile - and also some minor bruises of the head and face.

The body was not opened - these facts were ascertained by probing from the surface wounds.

(Sgd) Thomas Sinclair
Colonel AMS
Consulting surgeon IV Army
BEF

According to Sinclair, therefore, assuming that von Richthofen was sitting straight in his cockpit and the aeroplane was in level flight, the bullet must have struck him from the right side, was fired from an angle that was slightly in front of the body and was fired from below.
Captain Graham and Lieutenant Downs submitted a separate report on von Richthofen's death, a copy of this was also in the Bean papers at the AWM:

“Copy extract from AH File No. 21/13/506
We examined the body of Captain Baron von Richthofen on the evening of the 21st instant. We found that he had one entrance and one exit wound caused by the same bullet.
The entrance wound was situated on the right side of the chest in the posterior folf (sic) of the armpit; the exit wound was situated at a slightly higher level near the front of the chest , the point of exit being about half inch below the right (sic) nipple and about three-quarter of an inch external to it. From the nature of the exit wound we think that the bullet passed straight through the chest from right to left, and also slightly forward . Had the bullet been deflected from the spine the exit wound would have been much larger.

The gun firing this bullet must have been situated in the same plane as the long axis of the German machine and fired from the right and slightly behind the right of Captain von Richthofen.

We are agreed that the situation of the entrance and exit wounds are such that they could have not have been caused by fire from the ground.

Sgd G. C. Graham
Capt. RAMC
MO i/c 22nd Wing RAF
Sngd G. E. Downs
Lieut. RAMC.
In the Field
22/4/18

Graham and Downs referred to the exit wound being on the right side; Bean made a note that this is likely to be in error. If the exit wound was on the right side, it is unlikely that such a wound would have been mortal and it is generally accepted that Graham and Downs had made a mistake.
However there still remains the last paragraph of their report attributing the fatal bullet to a shot from the air, not the ground. If, as they considered, the bullet had not been deflected by the vertebral column, then the track of the bullet must have been laterally from below and behind the midline. However the only way that their statement that: “The gun firing this bullet must have been situated in the same plane as the long axis of the German machine” could be correct would be if von Richthofen had been twisting his trunk almost 90 degrees to the right and looking sideways or backwards when he was struck.

According to Newton, a Medical Board consisting of Colonel Barber, Major C. L Chapman, Australian Medical Corps, Major D Blake and Captain E G Knox of No 3 Squadron , AFC, examined the body a second time. This must be the inquiry under the presidentship of the Director-General of the Australian Army and Air Force Medical Services (Colonel Barber) referred to by Titler but Titler’s account is at variance with that of Newton when he stated that Colonel Nixon, Colonel Sinclair and Major C L Chapman were the medical officers present.

There is no record of any report made by this Medical Board in the Bean Papers. However, in 1935, Colonel Barber wrote to Bean and this letter is now quoted in its entirety, apparently for the first time. The underlining is original:


Oct 23 1935
My dear Bean,
With reference to your letter of October 14th. asking for information.
I was inspecting this Air Force Unit and found the medical orderly washing Richthofen's body so I made an examination. There were only two bullet wounds, one of entry, one of exit of a bullet that had evidently passed through the chest and the heart. There was no wound of the head but there was considerable bruising over the right jaw which may have been fractured. The orderly told me that the consulting surgeon of the Army had made a post-mortem in the morning and I asked how he did it as there was no evidence. The orderly told me that the cons. surgeon used a bit of fencing wire which he had pushed along the track of the wound through over the heart. I used the same bit of wire for the same purpose so you see the medical examination was not a thorough one and not a post mortem exam in the ordinary sense of the term. The bullet hole in the side of the plane coincided with the wound through the chest and I am sure he was shot from below while banking.

I sent a full report to General Birdwood at Australian Corps and I have often wondered what became of it.

With kind regards,
Yrs sincerely
George W. Barber

Colonel Barber enclosed a diagram of the bullet wounds on the body with his letter. In this he clearly showed the entrance wound in the left posterior axillary line at about the level of the ninth rib, and drew a cross over the right chest, internal to the nipple on the AP view. Under the diagram he wrote:

“Richthofen approximate sites of exit and entry of bullet. I forget now which was which but think the site of entry was the one in the back. G. W. B.”
(This diagram, however, is at slight variance with the other medical reports, quoted above, as both agree that the exit wound is external to the nipple. )
Barber’s letter clarifies the probe used by Sinclair; a surgical probe is a rigid piece of metal with a smooth rounded bulbous tip that is designed to avoid making false passages in the tissues. A ‘piece of fence wire’ is flexible and has a cut end, this would certainly not have been rounded and would have been prone to catch in the tissues, particularly the light air filled tissues of the lung. Barber’s letter, therefore, casts profound doubt on the accuracy of Sinclair’s report. It would have been possible to have used such a probe to examine the exit wound and determine that the bullet track involved the heart, but it would have been quite impossible to determine the track of the bullet to the vertebral column by using such a probe from the entrance wound.

Other difficulties in Sinclair’s report that the bullet was deflected by the vertebral column have been carefully addressed by O’Dwyer in 1969 (8). Dwyer sought medical opinions on the extreme difficulty in probing lung tissue. The elastic lungs would collapse as soon as air enters the pleural cavity (the space between the lungs and the chest wall), and it would be impossible for a probe to detect any perforation of the lungs made by a bullet.

From a consideration of the above, one is drawn to the conclusion that the fatal bullet must have passed directly through the chest from its entry wound at the posterior axillary line (the back of the armpit) at the level of the 9th rib (that is at about five inches below the lower level of the outstretched arm). As there is no real evidence that the bullet hit the vertebrae the most probable trajectory of the bullet would have to be along a line joining the entrance and exit wounds. Such a line indicates that the bullet was fired from the side, behind and below the pilot’s body, notwithstanding his position in the cockpit.

As the exit wound was about three-quarters of an inch external to the left nipple this means that the bullet would have passed through the heart and would have been rapidly fatal. Von Richthofen would have lost consciousness within 20 to 30 seconds, and certainly could have not continued to fly his aeroplane and fire on Lt. May for over a minute (9).

It is possible to correlate the medical evidence with that of the eyewitnesses of the last flight. Fortunately, as the events took place at low altitude, directly over the Australian lines, the chase and crash were witnessed by many eye witnesses.

EYEWITNESS REPORTS OF 21 APRIL 1918.
Bean's quoted reports are taken from official documents available in the Bean Papers or are from correspondence with the protagonists. Titler accepted many of Bean's quotations but also corresponded directly with Gunner Buie and Carisella and Ryan also corresponded directly with many of their witnesses.

There are several unpublished, or only partly published documents, in the Bean Papers, these have either been omitted or only partly quoted in Volume V of the Official History, and the originals of these documents cast new light of the events of that day. From the Bean Papers, and the Carisella accounts, it is now possible to advance the following description of what actually happened.

There is no doubt that von Richthofen followed a Sopwith Camel, flown by a relatively novice Canadian pilot, Lt Wilfred May, down from a dogfight that occurred when two British photographic reconnaissance R.E. 8 aircraft were attacked by von Richthofen’s Jasta west of Hamel. Carisella and Ryan describe the attack in detail quoting from a letter to the authors from Lieutenant Banks, (10) the observer and gunner aboard the second R. E. 8. The presence of the German triplanes was seen by a formation of eight Sopwith Camels, led by Captain A Roy Brown, DSC, a Canadian flying with the newly formed Royal Air Force.

Lieutenant May, who had been told by Brown that he should observe any action, but should run for home if attacked, was seen by von Richthofen and pursued. According to his instructions May dived away and flew low over the Australian lines, flying down the valley of the Somme, closely pursued by Richthofen. Captain Brown saw the chase and dived from behind on von Richthofen’s triplane at about 11 AM.

Brown's combat report, written after his return to Bertangles airfield, is partly quoted in Bean but fully quoted in Carisella and Ryan (11). According to them, Brown wrote:
At 10:35 A. M. I observed two Albatross burst into flames and crash. Dived on large formation of fifteen to twenty Albatross scouts D. V.’s and Fokker triplanes, two of which got on my tail and I came out. Went back again and dived on pure red triplane which was firing on Lt. May. I got a long burst into him and he went down vertical and was observed to crash by Lieutenant Mellersh and Lieutenant May. I fired on two more but did not get them.”
Carisella refers to a five part article entitled “My Fight with Richthofen” which was published in the late 1920s and attributed to Brown. Brown was quoted as having said:

I was in a perfect position above and behind. ... neither plane, (Richthofen or May) was aware of me ... I had dived until the red snout of my Camel pointed fair at his tail. My thumbs pressed the triggers. Bullets ripped into his elevator and tail planes. The flaming tracers showed me where they hit. A little short! Gently I pulled back on the stick. The nose of the Camel rose ever so slightly. Easy now, easy. The stream of bullets tore along the body of the all-red tripe. Its occupant turned and looked back. I had a flash of his eyes behind the goggles. Then he crumpled - sagged In the cockpit ... Richthofen was dead. The triplane staggered, wobbled, stalled, flung over on its nose and went down. The reserve trenches of the Australian infantry was (sic) not more than 200 feet below. It was a quick descent. May saw it. I saw it as I swung over. And Mellersh saw it."
Carisella and Ryan are disparaging about this article and stated that Brown was not the author. In fact they stated that it was: “Dramatic copy but obviously so much humbug. Brown was not a professional writer; the above report is written in the colourful slick manner of the hackwriter of the period.”

There is a reference in the Bean Papers to this article. Bean wrote to Brown in Canada on the 14 October, 1935 drawing attention to Richthofen flying for a considerable distance and still firing at May, “according to an article in a newspaper, the Chicago ‘Sunday Tribune’ of 22 April 1928".

Brown replied in a letter of 7 November 1935 that he had never read the account and wrote: “It is impossible for me to state how accurate the article had been” and referred Bean to the Official History of the RAF.

Although Bean had researched, and corresponded, widely in preparing his appendix on Richthofen, there is very little supportive evidence for Brown’s report in the Bean Papers. Indeed there is only one witness who suggests that Captain Brown shot down the red Fokker triplane, and even this is an indirect statement. 2nd Lt Mellor, RFC was quoted in the Melbourne Herald newspaper of 26 February 1930 and the clipping is in the Bean papers:

...Captain Brown seeing May’s predicament, followed the red Fokker and closing up to a range of about 100 yards, fired a long burst from both guns. I could see his tracer hitting the cockpit of the Fokker. The German machine zoomed, banked steeply and obviously crippled glided down to land between the Allied and German lines. He landed under control so the machine was not damaged.... The Australian Lewis gunners certainly hit the machine but their bullets hit about two inches behind the pilot’s seat.”
The only reference to 2nd Lt Mellor in the voluminous literature on the death of von Richthofen is a footnote to Bean’s Official History (12) . Bean wrote:

A Lieutenant Mellor wrote to the Melbourne Herald on 26th February 1930, giving as an officer of No. 200 Squadron a similar account. Efforts to confirm his account by reference to the Squadron’s records in London have, however proved fruitless despite a search kindly made by the authorities there.”
Lieutenant Mellersh, who was flying with Brown, was a witness to the crash of the triplane but he did not see Brown engage the Fokker. His account, printed in Titler, describes Mellersh as having engine problems and “...I was forced to spindive to the ground and return to our lines at about 50 feet. Whilst so returning a bright red triplane crashed quite close to me and in looking up I saw Captain Brown’s machine.”
Despite Brown’s statement that the triplane crashed after he had fired on it, von Richthofen did continue to follow May down the Somme valley at a low altitude. He appeared to be completely absorbed in his chase and, as he came within range, he came under fire from Australian anti-aircraft machine guns. In particular there was a Vickers heavy machine gun, under the command of Sergeant Cedric Popkin, which was situated about 1000 yards west of the village of Vaux on the northern bank of the Somme River, and the 53rd and 54th Batteries of Lewis guns, on anti-aircraft pole mountings, on the eastern slope of a shallow hill about 1000 yards east of Bonnay.

As he came to the hill, Lieutenant May, hugging the ground contours, rose to clear the rise and flew on in a straight line after passing it. The red triplane, still following May, also rose to clear the hill but then came under Lewis gun fire from the 53rd and 54th Batteries. It then performed an Immelman turn to return back to the German lines. This aspect of the fight was observed by Gunner George Ridgway, from Lang Lang in Victoria, who was on top of the Heilly brick stack near the Bray-Corbie road and who had an excellent view. Part of Ridgway’s statement is in Bean, (13) the full statement, taken by the Lang Lang correspondent of the Melbourne Herald, after being rejected by his newspaper editor, was sent to Bean. It is available in the Bean Papers. The full text is as follows:

He states that he was about 200 feet from the ground. The first plane passed to the right and rapidly began to climb. As soon as it was out of danger the machine gunners opened out on the German. Von Richthofen, he claims, came within 200 feet of the ground and to save himself he swerved to the left and immediately banked at an angle of 75 degrees. He was sitting upright in the cabin and could be seen plainly at the controls. All this occurred within 100 yards of the Heilly chimney stack.
The first plane having reached a safe altitude, the German plane provided an excellent target for the machine guns who were in a circle around him at Vaux-sur-Somme, Bonney (sic) and Corbee (sic) and thousands of rounds were fired at him, to use Gunner Ridgway's words, "A rain of death bespattered him."

The plane seeking frantically to escape only rose about 500 feet when it turned over to its left, and crashed to the ground.“Gunner Ridgway, who still retains the number plate of the machine was one of the first at the scene. On the number plate are the words: “Militar Fluzzeug (sic) Fokker DR. 1525/17". (14) He is emphatic that the Baron was alive when he banked after the other planes had gone . The nearest plane to him was at least half a mile away. He states that there was plenty of evidence to show that Captain Brown did not get him and hopes that the official War History will be amended even at this late date.

A. W. Madge
Lang Lang correspondent.”
However, although an indirect quotation, Ridgway’s reported statement is confirmed by Lieutenant G. M. Travers MC who wrote a report that is partly quoted in Bean (15) and is continued in the Bean Papers. Travers was observing near 11th Brigade HQ when he heard planes approaching from the direction of 26 central, and heard a Vickers gun firing from the ground. He wrote:

April 1918.
The first plane that came into view was one of our own, and less than 20 paces behind him was an enemy plane painted red. The red plane was overhauling our plane fast and both were flying so low that they almost crashed into trees at the top of the hill. Almost directly over the spot where I was lying the enemy plane swerved to the right so suddenly that it seemed almost to turn over. Our plane went straight on, from that moment the enemy plane was quite out of control and did a wild circle and dashed towards J.19.b.34 where it crashed. I went over with other officers and had a look at the plane and also the driver, who was dead, a machine gun bullet had passed from the left side of his face and near bottom of jaw and came out just behind the right eye (16)...The Vickers gun mentioned was the only gun firing at the time the driver first lost control of his machine. I made enquiries and found the gun was handled by No. 424 Sergt. Cedric Basset Popkin, 24 Australian Machine Gun Company.
G. M. Travers Lieut
Company 52nd Bat AEF

Further confirmation that Ridgway’s story is correct also came from Lieutenant J. A. Wiltshire, MC who wrote a letter to Bean on 9 June 1934. This is only partly reproduced in Bean and the relevant parts of the original letter (17) are as follows:

Dr C. E. W. Bean
Dear Sir,
In reference to Richthofen’s death. Standing on a ‘Farm Track’ close to the Mericourt, Corbie road about two kilos almost due south of Heilly.
Looking east I saw a fight in progress in the air. Three planes, two British and one German dived out of the fight. The German on both their tails, (18) one British plane dived out towards the Somme, the other with the German on his tail, continued toward the ground out of my sight. Within minutes, from the east, they appeared over the rise and flying about 40 feet from the ground. Passed almost over head.

The British plane was flying up and down the German flying to imitate and giving quick bursts with his gun. The German pilot seemed to crouch forward as he gave each burst. The British plane had apparently no tail gun as he did not reply.

The British plane steeplechased a group of trees and swooped down over the Ancre and continued his course between Bonnay and Heilly to the rear lifting over the trees the German plane gave up the chase and banking to his left straightened his plane toward his line and commenced to climb. He now came under machine gun fire from the ground. His plane would be just about overhead of the artillery. The plane seemed to steady and then headed slowly for the ground. Landing on the Somme side of the high ground...”
Sergeant Popkin’s Vickers gun position was situated at the foot of the hill at Bonnay, one kilometre to the south-east of the Lewis gun battery manned by Gunners Buie and Evans, and just to the south of the German triplane’s flight path. Popkin was ideally situated to fire on von Richthofen when he turned to the right away from the fire of the Lewis gun battery on the hill.

Popkin wrote a letter to Bean (19) on the 16 October 1935:

The planes would be travelling in a North East direction straight towards my gun position. I opened fire immediately the British plane left my gun sights and followed the fritz around. He would be perhaps 100 to 120 yards in front of me when I opened fire and about 200 to 400 feet in the air. He would be below the top of the ridge which is about 500 to 600 feet high. I opened fire the second time at the peak of his turn marked X. I dont think that I was firing so long the second time as the first. I would be firing at him the second time while he was travelling the line between the two crosses (20).
I would be firing about half to three-quarters a minute each time.

I reached the plane just when they were about to place a guard on it.

A chap named Marshall my No. 3 on the gun at the time who was afterwards killed got a bullet off Richthofen’s body which had just penetrated his clothes and half sticking in his skin right on his belt line.

Yours faithfully
C B Popkin
From Popkin’s letter it is apparent that Popkin missed when he first opened fire. The German triplane was heading towards him when this happened. He then fired for the second time and was firing as the pilot of the triplane was going away from him whilst banking. This is quite consistent with Popkin firing a bullet that entered von Richthofen’s body at the ninth rib in the posterior axillary line. The angle of Popkin’s fire was quite consistent with the trajectory of the bullet that killed von Richthofen, that is to say it was in a line from behind the midline of the pilot’s trunk and from below,

Further confirmation of Popkin’s letter is available from a letter from Popkin’s commanding officer, Captain F R Watts, in the Bean Papers:

19 11 29.
Sergeant Popkin allowed the British plane to pass and then fired at Richthofen who made a right swing and then came back to the gun and this time at a lower height when Popkin fired about 200 rounds at him and Richthofen swung round to the right and just managed to clear the ridge and crashed. I can assure you that there was no-one else had a chance to bring him down because there was no other guns close enough except mine.”
GUNNER BUIE’S CLAIM
Dale Titler wrote his book to support the claim of Gunner Buie that it was he who shot down Richthofen with his Lewis gun as the triplane approached the eastern slope of the shallow hill about 1000 yards east of Bonnay. Titler has quoted a statement attributed to Buie (21) as follows:

We were free to fire at any time without command, but as the planes neared us barely 50 feet off the brow of the ridge I was prevented from firing immediately as the two machines were almost in line, with Lt. May's plane blocking my line of fire.
Major Beavis and Lieutenant Doyle were on my right and left respectively, near Evan’s gun position, about 30 yards away. Lieutenant Ellis, on slightly lower ground at my centre, observed the oncoming planes from the flank and shouted, ‘Fire on that plane, Buie!’ But I still could not, owing to Lieutenant May's position.

I was swivelling my gun to follow the red machine, and Snowy Evans, manning the other gun on the opposite flank, got first clearance. He opened up at a range of slightly more than 300 yards. The triplane flew steadily on, still firing short bursts at the Camel it was now barely 20 yards behind and 10 feet above May. Very close indeed. I was at the ready with my finger on the trigger, waiting the clearance.

It came.

I can still remember seeing Richthofen clearly. His helmet covered most of his head and face and he was hunched in the cockpit aiming over his guns at the lead plane. It seemed that with every burst he leaned forward in the cockpit as though concentrating very intently on his fire. Certainly he was not aware of his dangerous position or of the close range of our guns. His position was much as a strafing attack would appear, and had he not been so intent upon shooting down Lieutenant May, he could easily have manoeuvred his machine and fired upon us, had he been so inclined. Richthofen and his men frequently strafed our trenches to the east.

At 200 yards, with my peep sight directly on Richthofen's body I began firing with steady bursts. His plane was bearing frontal and just a little to the right of me and after 20 rounds I knew that the bullets were striking the right side and front of the machine, for I clearly saw fragments flying.

Still Richthofen came on firing at Lieutenant May with both guns blazing. Then just before my last shots finished at a range of 40 yards Richthofen's guns stopped abruptly. The thought flashed through my mind —I've hit him! — and immediately I noticed a sharp change in engine sound (22) as the red triplane passed over our gun position at less than 50 feet and still a little to my right. It slackened speed considerably and the propeller slowed down although the machine still appeared to be under control. Then it veered a bit to the right and then back to the left and lost height gradually coming down near an abandoned brick kiln 400 yards away on the Bray-Corbie road.

I looked to my gun. It was empty. I had fired a full pannier....

Buie also commented on the bullet wounds sustained by Richthofen:
A guard was placed over the body and after awhile it was brought to our position. Major Beavis claimed the body for the 53rd and it was placed on a nearby stretcher. There I saw it. In the crash Richthofen's face was thrown against the gun butts and suffered minor injuries. Blood had come from his mouth which indicated at first glance that a fatal bullet had pierced a lung.
According to the popular version, death came from a single bullet which had entered his back and passed forward through the chest.

This was not true.

Richthofen was struck in the left breast, abdomen and right knee. (23) I examined these wounds as his body lay on the stretcher. His fur-lined boots were missing, as were his helmet and goggles and other personal effects, these having been taken before his body arrived at the battery. He was wearing silk pajamas under his flying clothes.

The wounds were all frontal. Their entrances were small and clean and the exit points were slightly larger and irregular in the back. Later, Colonel Barber of the Australian Corps and Colonel Sinclair of the Fourth Army, both medical officers, made separate examinations of the body and their reports agreed that the chest wound was definitely caused by ground fire. (24)

Interestingly there is also a very similar statement, also said to be told to Titler by Buie, published in a magazine in 1959. (25) However this differs from the statement published in Titler’s book in minor, but appreciable, detail. Although it was stated by Titler, in both publications, that this was Buie’s story, as told to him, the variation in the text of the two versions suggests that Buie’s story was not published verbatim but was, at least, edited by Titler.
CONCLUSIONS
Who shot Baron Manfred von Richthofen? There can only be four possible answers.

1. Richthofen was shot by Captain Brown.
The postmortem examinations revealed entrance and exit wounds from a bullet which must have entered the body from the right, from the side, from behind and from below the body as it was sitting in the cockpit. Such a track means that the bullet would have passed through Richthofen’s heart. Although Captain Brown did approach from Richthofen’s right, it is difficult to see how, firing as he did from above, he could have inflicted such a wound unless Richthofen was steeply banking his triplane at the time that he was shot. For what it is worth, the newspaper article in the Chicago ‘Sunday Tribune’, attributed to Captain Brown, did not mention such a bank. In this article Brown referred to Richthofen looking back at him when Brown fired at him and a steep bank therefore seems most unlikely.
Be that as it may, there is ample evidence from eye witnesses that Richthofen continued to pursue Lieutenant May along the Somme valley for about a minute, firing his gun and concentrating on his target. This would have been impossible if Richthofen had been shot through the heart by Brown.

2. He was shot by Gunner Robert Buie.
Again the track of the bullet makes it very unlikely that Buie could have shot Richthofen. From the statement attributed to Buie by Titler, Buie was firing when the triplane: “was bearing frontal and just a little to the right of me” and he could not have inflicted the wound that entered the body from behind. Buie stated: ‘Still Richthofen came on firing at Lieutenant May with both guns blazing. Then just before my last shots finished at a range of 40 yards Richthofen's guns stopped abruptly...” Therefore at no time did Buie fire at Richthofen from behind.
3. He was shot by Sergeant Popkin.
Bean and Carisella both came to this conclusion and this is supported by abundant eye witness evidence and by the track of the bullet Popkin first fired when Richthofen was approaching him from the Somme valley but he failed to stop Richthofen. After coming under fire from Buie and Gunner Evans, at the Lewis gun emplacement, the German aeroplane turned away from the gunfire and it was then, when the triplane was flying away from Popkin, that he opened fire with his Vickers gun for the second time. (26) Popkin continued to fire while the triplane completed the turn, and actually flew towards the Vickers gun, but there is no doubt that Popkin could have inflicted a bullet wound that entered Richthofen from below, from the side and slightly behind, just as was found at the postmortem examination. Neither Captain Brown nor Gunner Buie could have inflicted such a wound and it is therefore more probable than not that it was indeed Popkin who fired the fatal shot.
I say “more probable than not” because it is impossible to exclude the fourth possibility.

4. Richthofen was shot by an unknown Australian soldier who fired his rifle at the triplane as it flew over him and who scored a lucky hit.
This can never be disproved as the .303 rifle bullet was used by the Lee-Enfield Service rifle as well as the Lewis gun and the Vickers machine gun.
All that we can be sure of is that the entry and exit wounds on von Richthofen’s body meant that the bullet passed through the heart, or great vessels, and he could not have remained conscious for more than about thirty seconds after being hit. The fatal bullet had therefore to have been fired at von Richthofen at the end of the pursuit and this is likely to have been at the time when the triplane was observed to turn away from the hill where the Lewis gun batteries were situated.

SUMMARY
The Official post mortem examination report is, in all probability, flawed and it is most likely that the bullet track was along a line joining the entrance and exit wounds. In other words the bullet came from behind, below and lateral to von Richthofen. There is little doubt that the bullet penetrated his heart and was fatal. Neither Captain Brown nor Gunner Buie could have inflicted such a wound.

The only known gunner that could have done so was Sergeant Popkin when he opened fire for the second time when Richthofen was turning away from him. Richthofen then lost control of his aeroplane and crashed, he was dead when his aeroplane hit the ground.

From the evidence of the postmortem examination and from eyewitnesses it was therefore most probably Sergeant Popkin who fired the fatal shot, although a lucky shot from an unknown soldier firing his rifle can not be excluded.
http://net.lib.byu.edu/~rdh7/wwi/comment/richt.htm
https://en.wikipedia.org/wiki/Manfred_von_Richthofen

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