Hitler called off the capture of Moscow when the germans where 10 miles off.

Leningrad (st Petersburg) was sieged by the nazis in 1941 but very very late. If they attcked earlier it would of fallen

Nazi germany was an extreemly efficent war machiene in 1941 if they attacked earlier in the year as intended 100% they could of defeated the Soviets in the first year.

Historians seam to believe hitlers switch from attacking britians air inferstructure to civilin inferstructure was his second biggest blunder after stalingrad

Also the nazi navy where ment to change enigma codes monthly but didnt because they thought the allies would never break it. If they did change it ultra would of never been successful

Rommel had several opportunities to push deep into Egypt, he saw it as an opportunity to push thru and make a second front with russia whcih if he had of would of assisted with stalingrad. Hitler saw the egypt campaign as just helping the Italians

Nazi manpower wasnt weak till 1943. Even still it wasnt a lack of manpower but untrained troops especially tank crews.