not to get off topic but i agree with hilters invasion of russia in 1941 (summer)
1. needed resources
2. taking over crete/greece did longer then they thought but still victories
3. winter of 1941 was one of the worst winters off all time(bad luck) got screwed
4. the war going well eveyhwere else (from the north atlantic to North Africa)
5. russia was unprepared and also there mass of troops werent on the boader but ways back far after germany and russia split poland in 1939(easy first gains)
6. mobilzied army in the world (dont even compare to napolean since he had horses compared to hitlers panzers) but the t34> early panzer models 1-3
7. russia got beat up in finland in 1939-1940 winter time and gave off the idea they were weak and would break