Plüschow was a German naval aviator who was posted to the colony of Qingdao/Tsingtao/Kiao-Chow shortly before the outbreak of the First World War to fly one of two Etrich Taube monoplanes which had been sent out by ship to add to the defences of the port. War was declared soon after his arrival, and Qingdao was besieged and captured, three months later, by a joint British-Japanese force.

Plüschow did indeed claim, in his autobiography, to have shot down a Japanese plane during the siege, but his account has never, to my knowledge, been confirmed from the Japanese side, and must be considered unlikely, especially given the overall context of the claim. The relevant passage reads as follows:

Once I was busily engaged on my observations, when my aeroplane began to pitch and toss. I thought this was due to bumps in the air [this seems to be a poor translation of some German term for "turbulence"], caused by the many steep and rugged mountains of this country, which made flying extraordinarily difficult. Without even looking up, I went on taking observations, only grasping the control-lever with one hand in order to keep the aeroplane steady.

After my return I was informed, to my great surprise, that an enemy plane had flown so closely on top of me that they thought I should be shot down.

Next time I was more careful. And on sighting one of my enemy colleagues I followed and shot him down with my Parabellum pistol after firing thirty times.

Plüschow, My Escape From Donnington Hall (1922), pp.69-70

With regard to Plüschow's career as an escaper: he was able to escape the siege by flying out of the port, shortly before its fall, with final dispatches from the governor. After crash landing in China, he was eventually able to board a ship for the US and thence board a vessel headed for Italy. He was arrested when the ship was searched at Gibraltar, and sent to a prisoner of war camp at Donnington Hall in Leicestershire, arriving in May 1915.

Three months later, Plüschow escaped and made his way to London, where he swam out to a Dutch ship anchored off the port of Tilbury and was able to clamber on board and stow away unseen. He made it to the Netherlands and from there managed to cross the border back into Germany.

Plüschow's feat made him the only German to successfully return to Germany from British captivity during the First World War, but he was not the only one ever to do so. During the Second World War, a Luftwaffe pilot named Franz von Werra, who was being shipped to a POW camp in Canada, successfully escaped by jumping off the train transporting him into captivity. Von Werra made his escape in January 1941. He was able to cross the partially frozen St Lawrence river into the US, and from there travelled to Mexico, Brazil, Spain, Italy and finally Germany, arriving home in April 1941.

Unlike Plüschow, who was given a safe posting to command an air station in the Baltic after his return home, and who lived on to die in an air crash in Patagonia in 1931, Von Werra returned to active flying duties and was killed that same October when his plane experienced an engine failure and crashed into the North Sea.

Sources

Anton Ripon, Gunther Plüschow: Airman, Escaper and Explorer (2009)

Kendal Burt and James Leasor, The One That Got Away (1956)