2 Official inquiries both ruled he was shot down by Australians
(I posted most of this as a reply but thought it was worth it's own thread)
Firstly he was buried by Australians. The entire funeral was filmed and the film is still in existance. He was buried by an Australian Army guard of honour. The pallbearers were indeed airmen, but they were all from No.3 Squadron Australian Flying Corps who assumed responsibility for the body and the aircraft as soon as he was shot down.
I've also seen many 'documentaries' claiming the Red Baron (RB) on behalf of many sides. However it still doesn't change the FACT that he was shot down by Australian AAMG's. Most of the controversy had to do with politics. The British Royal Flying Corps was trying to prove that the best defence against aircraft was other aircraft (they were correct), while the Royal Artillery was claiming that the best defence was AAA and AAMG's. So both had a vested interest in claiming that their method shot down a very high-profile enemy aircraft.
Consider the facts:
The Canadian Pilot Brown's guns jammed over ten minutes before the RB was shot down and he left the battlefield.
Brown initially NEVER claimed the kill. It was later claimed on his behalf by the British Royal Flying Corps for the political reasons above.
Brown later acknowledged he didn't shoot him down.
Brown probably contributed to the RB being shot down as he forced the RB to lose altitude which put him close to the ground above a sector controlled by the 1st Australian Imperial Force. The RB often wrote that under no circumstances allow your aircraft to pass over enemy positions at low altitude. In the slow canvas aircraft of the time it was virtual suicide. Especially above an entire machine gun company.
The British Royal Flying Corps staged a commission of inquiry late in the war to establish he was shot down by aircraft. The commission found he was shot down by Australian AA Machine gun posts of the 24th Australian Machine Gun Company.
After the war the German Army disagreed with the idea that their greatest ace was shot down by ground fire (not in keeping with the image), and launched their own commission of inquiry to prove he couldn't have been shot down by ground fire. That commission ruled he was shot down by Australian AA and even specified which AAMG crew shot him down.
An autopsy was carried out on his body - The autopsy found he was killed by a .303 bullet fired from directly below which went through his leg off his ribs grazed his heart punctured his lung and exited through his shoulder.
Yet in spite of this, every novel and movie written about the RB has him shot down by Brown. Being shot down by AA just isn't dramatic enough for a story - there's no nemesis engaging him single daring single combat, just a grunt in a trench lucky enough to have an enemy aircraft sputtering along just above his gun sights.
But as I've stated - Two official inquiries created for the specific purpose of showing he was shot down by aircraft and both found he was shot down by AAMG.
Here's quotes from three people who were there - Two pilots and one a soldier on the ground:
"21/4/18 Richthofen crashed in the Australian lines in Amiens sector and was killed. The honour of shooting him down has been much disputed and a British squadron of Camels laid great claims to the honour. This 5th Division Artillery major and I were discussing the matter and he then told me:- “I was standing near the machine gunners attached to my unit and watching a glorious “dog fight” between Fritz and some of our Camels. Suddenly a Camel appeared very low, with a German right on his tail and our chap looked an absolute goner, as he could only fire ahead and the enemy was directly behind him. Then my gunners had a go from the ground, the German machine wobbled, fell and crashed, killing the pilot, who also had been hit through the chest by a bullet which it was evident had been fired from below him. From papers found on him it was discovered that the pilot was Richthofen.
Even now the matter is often discussed in the newspapers, “who brought down Richthofen?” and it at last has officially been admitted that Australian Machine gunners have the honour." - 4720 Flight Lieutenant Donald F. Day Nos 5 & 6 (Training) Squadron AFC
"From the first Von Richthofen appeared to outclass his man and was steadily driving him down and retaining the offensive position, but the R.F.C. Pilot by clever handling of his plane, although unable to get into an offensive position, made himself a very difficult target and was luring Von Richthofen further and further over allied territory and closer to the ground......
....... appeal to you Sir, and the Public to judge and give credit where credit is due.
There were many of the best Flight officers of the R.F.C. and A.F.C. and our Allies who were anxious for the opportunity regardless of risk, to try and do what a machine gunner on the ground had done without taking any risk at all, to rid the Allies of a very clever and dangerous enemy.
Most of those Airmen who were unfortunate enough to have that wish realised were later traced by a crashed plane and a grave somewhere in the enemy territory. I understand that it was officially stated in Germany that he had 80 Air craft of the Allies to his credit but a number of them were proved to be Kite Balloons. I believe although only conjecture on my part, that the germans thought that our squadron was responsible for decoying Von Richthofen to his death for we had many casualties in the next few weeks. " - 8431 Lieutenant Alec S. Paterson, No. 3 Sqn AFC
"Our A.I.F machine gunners on the ground had fired on a red Fokker which was chasing an R.N.A.S. Camel, very close to their position. They had fired on the Fokker, which crashed and that was Richthofen’s machine. They were given the credit by their Divisional General. The R.N.A.S. squadron must have had their claims in too, for I read when the war was over, that the R.A.F. had given the credit to one of their squadron’s Captains." - 424 Private Frank R. Rawlinson
As for an account of his funeral-
"We all got something as a momento. We photographed the body and he was buried that afternoon, Tuesday at 4.30. They obtained a coffin – Harold engraved the following inscription in plate for his coffin – Cavalry Captain Baron Von Richthofen aged 25 Killed in Aerial combat Sailley-le-Sec Somme France 21-4-18. There were three wreaths one from 5th Div HQ with German colors and the card read to a worth and valiant foe. Another wreath came from the Royal Air Force and one from our own 3rd Squadron each having the German colors.
We supplied a firing party of 25 men, he was given a full military funeral. Oh we had all the heads here – quite a dozen official reporters and a cinematographer from the War records Dept. Of course it seemed a down right shame that such a fuss should be made over an enemy airmen – no doubt he was brave man they all are, but unless they have proof that Germany treat our good pilots in a like manner I would be one to pass him by like they are known to treat our boys. On the morning of his fall Germany were sending out to the world news of his 80th victim but our men say he always fought fair – we stood to attention as 6 of our pilots carried him out to the car. He was buried at Bertangles a French Village but oh such a dirty forsaken hole." - 2237 Air Mechanic 2nd Class John A R Alexander, No 3 Sqn AFC