What were the causes of World War 2?

Answer 1

http://www.ducksters.com/history/world_war_ii/causes_of_ww2.php

Answer 2

This gives some background leading up to World War II in Europe:

http://militaryhistory.about.com/od/worldwarii/a/wwiieurcauses.htm

Answer 3

And this covers Japan, too:

http://militaryhistory.about.com/od/worldwarii/a/wwiieurcauses.htm

Answer 4

Sorry, that was a duplicate link. This is the one I intended:

http://www.worldwar2facts.org/causes-of-world-war-2.html