[DCBryan1]

Big assist by Hitler’s mistakes including his reign of terror in the Ukraine and other occupied terrorities when the Germans were first greeted as liberators by the Ukrainains and his decision to not immediately take Moscow and instead shifted forces south to surround Kiev.

Hitler's biggest mistake was to 1) attack Russia, 2) Attack Russia later than planned (had to send Armies into the Balkans to save the Italians). 3) Epic Fail on German intel in estimating a: number of Russian divisions, b: technical analysis on "new tanks" to confront with TTPs on how to defeat them (KV1,T34s)

[AustinBill]

Lots of errors in hindsight. Another major one was declaring war on the U.S. after Pearl Harbor in the mistaken assumption that their “ally” Japan would return the favor and declare war on Russia in the east. Had that not happened, Roosevelt would have been hard pressed to get a war declaration against Germany.