WW2 started in 1939. the US entered into the war in 1941. russia made the biggest contribution in defeating the germans:

[en.wikipedia.org]

The Battle of Stalingrad (23 August 1942 – 2 February 1943)[17][18][19][20] was the largest confrontation of World War II, in which Germany and its allies fought the Soviet Union for control of the city of Stalingrad (now Volgograd) in Southern Russia.
Marked by fierce close quarters combat and direct assaults on civilians in air raids, it was the largest (nearly 2.2 million personnel) and bloodiest (1.8–2 million killed, wounded or captured) battle in the history of warfare.[21] After their defeat at Stalingrad, the German High Command had to withdraw vast military forces from the Western Front to replace their losses.[1]

@callmedubious I sit corrected. ? I should have said 'we helped defeat Hitler'. Good catch.

@SwampBatman Everyone knows "America was never great" is a favorite chant one hears Trump haters yelling, so asking for when just rings of that sort of mordancy. The whole post just oozes with virulent sarcasm. I guess I could be wrong. If so, my apologies.

I agree.

@SwampBatman Too true.