Who caused the war? If you want to get technical then the Allied Powers of WWI did when they laid an oppressive burden on the German people at the end of the war in the form of the Treaty of Versailles. In effect, this treaty made Germany their ***** for the next few decades. Hitler? He started out doing great things for Germany. Eliminated unemployment, created jobs, turned a destroyed economy completely around. Then he got greedy and wanted more (as uncontrolled power always tends to do). He annexes the Czechs and Chamberlain, acting on what he believes at the time to be the best for the British people, lets Hitler keep it in exchange for a document promising peace. Hitler takes this to mean "I can get away with murder" and later takes Poland. Stalin, having killed off most of his military in the Great Purges of the '30s, sees Hilter taking over Poland (which they jointly raped years earlier) and sees his country unable to fight the German military machine, so he signs the non-aggression pact. Britain and France declare war over Poland. France does this to honor the alliance with Britain as they are woefully unprepared for the war, putting far too much faith in their wall between their border and Germany. Germany topples France in weeks after attacking through Belgium exactly like they did in WWI (which still amazes me as the French had no defensive provisions for this). France copitulates and Britain is beaten back to the Channel. Meanwhile, the U.S. aids Britain in every way possible short of open warfare as the U.S. needs the money and jobs generated by the Lend-Lease agreement and the U.S. military is in no shape to fight another major war. Germany then attacks Russia and Stalin is caught woefully unprepared as his trust in Hitler to honor the non-aggression pact was nearly his undoing. The Soviets finally stop the German advance outside of Moscow and push the Germans out of Stalingrad, and by this time the U.S. has entered the war after the Japanese attack on Pearl Harbor. Lend-Lease extended to the Soviets though it doesn't start arriving until 1943. Second front opened in France in 1944 and eventually Germany, fighting a losing war on both fronts, surrenders in May 1945. Japan follows suit in September after atomic bombings.
The Outcome:
United States:
- recovery from a major depression
- sphere of influence in Europe created by Treaty
- money generated from Lend-Lease
- loss of 400,000+ lives
Britain:
- end of Imperial era
- cities damaged by bombings
- massive war debt
- territories gained in Middle East
- loss of 380,000+ lives
France:
- occupied
- divisions between Free and Vichy
- country in ruins
- loss of 800,000+ lives
Germany:
- cities, industry, economy destroyed
- divided into zones of influence by victors
- loss of 7,000,000+ lives
Russia:
- much of western Russia destroyed
- sphere of influence in Europe created by Treaty
- loss of 25,000,000+ lives
Japan:
- loss of Empire
- cities in ruin
- demilitarized as result of Treaty
- nuked
- loss of 1,800,000+ lives
Looking at it from this perspective, the allies are clearly the victors with the U.S. coming of as the least worse for the wear. I attribute this to their entering the war two years after it started and the protected isolation of the United States mainland. I welcome debate on these issues.