I had always heard that the seeds of WWII were sewn at the very end of WWI, when anti-war activists (socialists and Jews) tried to erode support for the war, resulting in a disastrous defeat for Germany. Between WWI and WWII, German nationalists, still angry at socialists and Jews for causing the humiliating defeat of WWI, were more than willing to support a very strong nationalist -- Adolf Hitler. I had also heard that this was mostly cheap justification for the Nazis to increase their power.
It is often called the "stabbed-in-the-back" version of history, with socialists and Jews supposedly having stabbed the German army and its leaders in the back, even as they marched forward to victory in France.
In "The Burden of Guilt", Vogt discounts the stabbed-in-the-back view, mostly by blaming the harsh conditions of the Treaty of Versailles for the impoverishment and anger in Germany between the wars. German nationalists, according to Vogt, associated the new Republic, and democracy in general, with "self-abasement and dishonor."
From the book:
One may ask today whether it would not really have been right to reject the Treaty (of Versailles). If one side no longer wished to fight, then it could have passively allowed the victors to occupy Germany completely, and then the Allies would have had to take full responsibility for the occupied country -- as was the case after the Second World War in 1945. In 1919, too, they would have been forced to set up a government sooner or later, and would probably have realized much quicker that the economy of a nation, the foundation of its existence, cannot be destroyed with impunity. But, above all, German Nationalists would have been prevented from ever attempting to identify the new Republic and democracy with self-abasement and dishonor. The acceptance of the Treaty was to serve them as an excellent pretext for this form of propaganda.
(Field Marshal von Hindenburg) testified before the same body. He was asked some questions but he disregarded them; instead, he read a prepared statement along the lines that the army and the military chiefs had always done their best. The German people and the political parties, however, had deserted the men fighting at the front, and, in the words of a British general, "stabbed the army in the back."
...for many Germans drew comfort from the idea that the German army had remained "unvanquished in battle." The stab-in-the-back legend afforded them a rationale for their hatred of democracy, of the Republic, of anything new. Later on, it was grist for the Nazi mill and thus it turned into one of the most pernicious political myths of the recent past.
By all accounts Germans, just prior to WWII, were fed up with high unemployment rates and a general state of impoverishment. The reason so many followed Hitler into war may be as simple as a burdened, unhappy population willing to try Hitler's ideas for making things better. Throw in dictatorial power in the hands of a madman, secret police stifling dissent, an immense propaganda machine -- and the rest is history.
Why dig up old history?
WWII, which began to smoulder at the conclusion of WWI, was so deadly and destructive that it resulted in the formation of the United Nations. The UN, of course, created Israel in the heart of the Middle East just after the end of WWII. Much of the problems Muslims are causing today, especially terrorism, center on anger at the existence of the Jewish state in their midst. (Too, much of the anger is due to their willingness to follow their own dictators, who falsely blame external causes for poverty. And, one cannot discount the violent nature of Islam.)
I don't, however, consider the creation of Israel to be a valid excuse for suicide bombings, airplane hijackings, and flying planes into skyscrapers. Terrorists, by their very acts, are subhuman and should treated, and eradicated, accordingly.
Also, there are some parallels between the Weimar Republic and present day Iraq. From the book:
Thus, at its very beginning a major shortcoming was revealed in the Weimar Repubic: the fact that its political knowledge lagged behind its constitution. The constitution was designed for a democratic people. It presupposed an extremely high confidence in the people, and frequently left the final decision to them. In reality, however, many Germans still hankered after the previous state authority, and were neither ready nor willing to justify the confidence placed in them.
Note that this post is a gross oversimplification of detailed subject matter.