In my opinion Operation Barbarossa was the most crucial turning point in the war. Although Operation Sea Lion and Pearl Harbor had their own significant contributions, Operation Barbarossa managed to weaken Germany’s moral, their forces, and split their army into two fronts. It is to my belief that Germany’s two front war is the main reason they lost in the first place. Hitler invaded the USSR with all intentions of taking of abruptly, however, with the combined efforts of Russ