Why did the newly eatablished democracies of europe have trouble surviving in the years after world war 1

Much of their resources had been depleted during the war, especially on the losing side.  What also added to this factor was that many towns and cities had been destroyed, and much of the farmlands and crops were damaged also.  So not only were the governments weakened after the war, they were also lacking soldiers to defend themselves in case of another war.  Germany eventually built up an military to start WWII later on in 1938 - 1939.