Boxer Rebellion 1900, Chinese soldier fights the German embassy. Chinese soldier is captured by the Japanese in the defense of China years later. He is impressed into the Japanese army and fights the Russians in border conflicts in the late 1930's. Then he is captured by the Russians and is impressed into the Red Army. He then fights the some of the same embassy staff from 1900 only this time as a Russian soldier rather than as a Boxer.
There were some similar actions that happened in WWII, with Koreans fighting in the German Army and captured by the Americans at Normandy.
Mike "Bunkermeister" Creek
but if our brave Soldier even was a very young member of the Society of righteous fists of Harmony of 12 years only, he will be 50 Years old to be captured by the Red Army at, let us say Nomonhan and nearly 60 when he will fight in the battle of Berlin.
O.K., he will be very tough if he survives the hardships of the Boxer Rebellion, the Warlord Era, the Soviet-Japanese Border War and the second World war, but will really someone press a 50+ Soldier into his Army?
O.K., there where some Germans that fought in 1864 versus Denmark in 1866 versus Austria-Hungaria, 1870 versus France and marched with the German Army into Belgium and France in 1914, what is also a span of 50 years, but this where really few and, as I think, mostly posing old men for propagandist reasons. Not real Combatants.....
From my point of view should everyone over 50 on a Battlefield wear the Stars of a General or should be at least some kind of NCO that is nearly 60. And such guys are not longer seen in the Front line, as i hope......
One Suggestion, let the Boxer Rebellion and start with the Tsing-Hai Revolution 1911. Then your Fighter is in his 40´s in 1945 and still able to fight.