Answer:
They all worked together to defeat Germany. The British, Canadians, and Americans landed in France to begin the Western Front for Germany and Russia with one major counter attack was progressing quickly towards Berlin.
Step-by-step explanation:
They did this through what I think were better tactics then the Germans and by taking out Italy from the game. Liberating Italy and destroying that line of support for Germany made the war in Europe much easier for the Allies. Also towards the end of the war Germany's army or the Wehrmacht was suffering logistically and with morale.