You could say the "Spanish" Flu (it actually started in the U.S.) is also responsible. At the post WWI negotiations American President Woodrow Wilson was taking a somewhat generous position toward Germany, more in the direction of the Marshall Plan after WWII. French Prime Minister George Clemenceau took a much harsher, perhaps even vindictive, approach. The discussions were stalled, but then Wilson got the Spanish Flu and was knocked out of action, and so Clemenceau prevailed. Lots of circumstances combine...