When Hitler, in violation of the Treaty of Versailles, decided to rearm in1935, the signers of the Treaty did nothing. It was a bluff on the part of Hitler, and it paid off handsomely. He learned that his European opponents were wimps. So he marched into the Rhineland in 1936 in another violation of the treaty. Again nobody did anything about it. He then laid claim to the Sudetenland of Czechoslovakia, and the naivete of British P.M. Neville Chamberlain allowed him to annex it as long as he did not annex any other territory. Well Hitler lied and promptly marched into the rest of Czechoslovakia. It was another bluff that paid off. Then in 1938 he took over Austria. Hitler was weak in 1935, and the French could easily have beaten him in a conflict. But no, they did nothing. Finally when WWII started in 1939, Hitler had the largest army in Europe. His opponents had lost their chance to easily stop him.
Neville Chamberlain was more interested in peace than stopping an aggressive Hitler, and he lived to regret it.