Opinion:
“Taking the longer view, you might argue that World War I caused World War II -- or at least, the Versailles Treaty that ended World War I caused World War II. By imposing such harsh conditions -- especially huge reparations payments -- on Germany, the treaty led to Germany's economic collapse by the 1930s, which then fueled massive resentments and anger among the German people, who then supported Adolf Hitler, who turned those resentments into support for his own aggressively militant regime. Maybe a more just peace after WWI would have meant that Hitler never rose to power and WWII never happened?”
Opinion:
“Unchecked aggression from Hitler's Nazi Germany in Europe and from Imperial Japan in the Pacific eventually made it impossible for the western democracies to avoid fighting back, even though they really tried to avoid the war.”