Germany, Italy, and Japan initiated a policy of aggressive territorial expansion. Japan attacked China, Italy invaded Ethiopia, Germany (under Hitler) immediately began to build up armed forces (a direct violation of peace treaty)
Germany then invaded many countries, including Austria, Czech, Polland, Norway, Denmark, Belgium, Netherlands, and France.
US (under Franklin Roosevelt) announced neutrality. Roosevelt's plan was to defeat the Axis nations by sending the Allied nations war supplies. Roosevelt stopped all exports to Japan and refused to let them withdraw money from American banks. Japan bombed US at Pearl Harbor, causing US to join in war.
After victory was atttained in Europe, focus went to Japan. 2 atomic bomb were dropped and the Pacific war ended.
Allies agreed that Germany's armed forces be abolished and Nazi Party outlawed.
Outcome: United Nations named for promoting world peace.
Consequences: death, destruction, displaced people, strength/spreading of Communism/Cold War tension (ended more lives and caused more devastation than any other war)