You're talking about Operation Sea Lion, the German plan to invade Britain. The invasion would have required air supremacy, which Germany lost following their defeat in the Battle of Britain. Additionally, after taking heavy losses in the Norwegian campaigns, the German navy could not secure the channel and protect the landing craft from the numerically superior Royal Navy. I agree that invading the Soviets was a terrible idea, as we all know, one should never get involved in a land war in Asia.

You're correct that Eisenhower lead the largest amphibious invasion in World War II. Less well known, however, is that the allied amphibious assault of Sicily (Operation Husky) was larger than the Normandy landings (Operation Overlord). Operation Husky consisted of seven allied divisions; D-day consisted of five allied divisions.

Yea, I just finished my military history final two hours ago :)

Be wary of fundamental attribution error which "describes the tendency to over-value dispositional or personality-based explanations for the observed behaviors of others while under-valuing situational explanations."