If you are knowledgeable of history please answer. No need for a detailed answer necessarily just hit on the main points.
Some points that I think are important are the fact that world war II was caused because most of the world was living in poverty beause of the Great Depression. The Great Depression of course being caused by the economic boom created by monetary expansion of the central banks and then Hoover and Roosevelts socialist policies.
They couldn't agree on whether there were 79 or 78 episodes of Star Trek.
WW2 technically started when England declared war on Germany when Germany declared war on Poland.
Both one and two:
Upsets in the balance of power.
I agree with the above posters for the most part, however, US involvement in the wars is a lot more questionable.
The security dillema was probably the biggest contributor to World War I. Security dilemma or Spiral model is a term used in international relations and refers to a situation in which actions by a state intended to heighten its security, such as increasing its military strength or making alliances, can lead other states to respond with similar measures, producing increased tensions that create conflict, even when no side really desires it.
http://en.wikipedia.org/wiki/Security_dilemma
This wasn't something new in Europe especially since Germany was essentially the main military superpower in the region. Tensions built up as states formed alliances to counterbalance the main threat with other states bandwagoning with Germany. World War II in my opinion was largely influenced by the United States involvement in the first world war. Had Germany and her allies had won the results would have probably been in the same as any other war in Europe. However The United States allies wanted revenge against Germany(France especially since Germany had annexed a large chunk of them prior to WWI) which resulted in the Treaty of Versailles.Everything else is pretty much self explanatory since that contributted to the rise of Nazi Germany.
I can't give much more than a book reference, and what I remember as I don't have it with me, but
Dreadnought: Britain, Germany, and the Coming of the Great War [http://www.amazon.com/Dreadnought-Britain-Germany-Coming-Great/dp/0394528336]
but this goes through and tries to explain it through various political and family issues [putting some blame on Queen Victoria]
I am not sure how good it is for pure history, but puts some interesting ideas out there.
World War II started in the manner did because Franklin Roosevelt decided in the mid 1930's to threaten to block aid to Britain if Britain did not guarantee the independence of Poland. It put Britain into the situation with following view of options: (1) Allow Germany to annex the German parts of Poland that it wanted and risk having to eventually fight Germany anyway with no intervention from the U.S. (2) Declare war on Germany and guarantee intervention by the U.S.
Hart, Basil. 1970 History of the Second World War. (See also Hart's essay in his book on the Soviet Army in the 1950's, and Rezun's Icebreaker).
Guyot, Yves. 1916. Causes and Consequences of the War.
WWI: German militarist and protectionist attitude, that was also popular in other countries. German naval build-up with aim of getting more colonies (also this is what Mises thought made the war inevitable).
WWII:
Proximate Cause:
USSR campaigns 1930-1933 to aid Nazis as opposed to German Social Democrats (whom Stalin thought were of capitalist "morality" for refusing to use violence against "class enemies").
Soviet Union in 1939 allowing Germany the ability to fight only one front (west) by allying with it, calming German fear of confronation with Russia while they attack Poland and France. This tipped Germany in favour of risking war to obtain self-defined "additional living space".
French error in positioning tanks (which they had more of than Germans, allowing Germans to defeat them) and USSR screw-up of signalling to Germany preparations to attack Germany by positioning after German and USSR split of Poland near the Rummanian oilfields.
Ultimate Cause:
Worldwide militarist and protectionist attitudein Germany and Japan and Italy after bank crisis, idea of territorial expansion into West by USSR through German icebreaker, protectionist and attitude by Britain and USA, which up to beginning of war sympathized with the protectionism and planning of national socialists and the Russian socialists.
Protectionism = ideology of gain by conflict as opposed to cooperation via exchange.
Profiteering by the power elite. /thread.
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Clayton -
A mayor contributing factor to WWI was the mistaken idea that a general European war would look much like the First and Second Balkan Wars, which were essentially decided in one month, had looked like. Had they known what awaits them it is doubtful any of the powers would had entered it. Without knowing this all the other reasons for war will seem extrodinarily trifling.
For the Second World War it is important to understand that the British and the French assumed that in a war between Germany and the USSR, Germany would triumph easily. Therefore standing by as Hitler and Stalin fought it out was not an option to them.