Finally, however, Hitler pushed France and Britain too far, and they jointly declared war when Germany invaded Poland in September 1939. But France remained exhausted and in no mood for a rerun of 1914–18. There was little enthusiasm and much dread in France at the prospect of actual warfare after the Phoney War. When the Germans launched their blitzkrieg invasion of France in 1940, the French Army crumbled within weeks, and with Britain retreating, an atmosphere of humiliation and defeat swept France.