Gents, I realize that I've been coming across with a tone of the Russians being the best thing since sliced white bread relative to WW2, which isn't true. Hitting on the main countries represented on DFS:
The US:
Fought a nasty enemy on the Pacific front. The closer we came to Japan, the worse they were. We lost a lot of good men on that front.
Manufactured and shared critical weapons.
Won the peace after the war.
Were critical in demolishing Germany's ability to make war, at a great cost to our men. I won't go look it up, though I believe casualties were 70% for bomber crews flying into Germany until the P51 Mustang long range fighter was available.
I am amazed at how quickly we were able to change manufacturing to produce military equipment.
Canada:
Canada fought above its weight. Don't let their 'niceness' fool you. The gloves come off when needed.
I'm not sure how much this was the case in WW2, though currently their snipers are among the best, if not the best, in the world.
Britian:
A heavy hitter in WW2 any way you look at it.
Won the Battle for Britian.
Were awesome cryptologists. While not sexy, breaking the enemies code was a very big deal.
Australia
They were in from the beginning, sending troops to Europe before having to pull them back.
I don't have examples, though they were fighting for their lives to keep the Japanese from invading, thus I feel sure they fought above their weight.
France:
The issue with France was that the military and country's leadership didn't have the stomach for a fight. This did not apply to the soldiers. They fought valiantly, killing nearly 50,k Germans in the short duration of the Blitzkreig. I'm pretty sure many of them sacrificed themselves to enable the escape at Dunkirk.
Their resistance was very helpful.
The rest of Western Europe:
They did what they could and were part of the resistance.
A lot of people in these countries helped Jewish people.