Every world war

In both world wars, the USA joined late when the fighting was already happening for several years. The only reason they joined WW1 was because of the Zimmerman Telegram, and they only joined WW2 because of Pearl Harbor. While there wasn't a nation in WW1 that gave greater help than all the others, the real reason for the Allied victory in WW2 was the Soviet Union.

Fair enough, but the Soviet Union was begging America to open up a new frontline so they could catch a break. The frontline was in a pretty unhelpful area for the Soviets though, so they probably could've persevered and won the war without American assistance. So yeah, I guess you are right about that.

Yeah, the Soviets experienced the worst of the fighting

They barely did a single thing in WW1, the British carried the entente