All the allies won WWII. The US came in late because Japan bombed the shit out of them. WWII spanned Sept 1939 to Sept 1945. In that time, the UK lost 383,000 soldiers, about 63,833 per year.
In steps the Americans because Japan forced them to. Dec 1941 to Sept 1945, just under 4 years, you could say part timers. The part timers lost 407,000 soldiers, technically over 101,750 per year.
America would have lost more soldiers if it wasn't for the Brits taking command of their troops. And to top it off, some retarded Americans think they won WWII for the planet. Those are a special type of idiot with absolutely no knowledge of any history beyond their doorstep. In fact, they probably don't know the casualties per country.