I asked a question here earlier today about Hitler's invasion of Poland on Sept. 1, 1939.
The (incredibly informative, detailed) answers people gave me were chilling. In case you're as not-up-to-speed on WWII history as I was (not), I'll summarize:
1. The nationalistic, xenophobic "philosophical" foundation that led to Hitler's supposed plan to unite all Germanic "Volk" had been laid over the 50 years or so before Hitler's rise to power.
2. Hitler planned the invasion well in advance, then devised a propaganda excuse to justify it.
3. The propaganda excuse was a false-flag attack on a radio station near the Germany-Poland border. It involved German soldiers posing as Polish soldiers and prisoners "posing" as dead Polish officers.
4. Hitler proceeded despite pleas to the contrary from other European nations and Britain.
5. Hitler justified the invasion as "self-defense."
6. By the time of the invasion, no German government official was willing to oppose Hitler.
7. Most Germans opposed the invasion but lacked the will to stop their crazed government.
If you're interested in more detail, the original thread is here.
http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=364&topic_id=2031286&mesg_id=2031286