I would state pass on Great Britain's military battled the hardest. The thing about Great Britain that causes me to think of it as a victor during world war 2 is that it was the first ally(other than france) to get included. Likewise the brits were never really involved by the German's nor some other nation around then. They were besieged mercilessly for a year and did not surrender did not give up.
Ontop of this the general population their upheld the military which made everything(the capacity for them to remain in the war)possible. Extraordinary Britain as I would like to think was the hardest battling military during world war 2. That being said I additionally regard the Soviet Union's military during that timeframe. As an American it's difficult for me to think about some other nation doing great during world war 2, yet I really feel Great Britain did the best.