After World War One, because of the Treaty of Versailles, the armed force of Germany was limited. Even though Hitler rearmed the German army, it was still not powerful enough compare to the power of Britain and France. However, one of the most important reasons for Hitler to control most parts of East Europe was the appeasement. It was the political strategy of pacifying Germany in the hope of avoiding a war. The powerful countries were trying to prevent the war, so that the small countries had to sacrifice.
On March, 7th, 1936, Hitler ripped the Treaty of Versailles by ordering 35 thousand soldiers to invade Rhineland. Comparing to the number of the French soldiers, there was a huge distance. Therefore, before they invaded Rhineland, Hitler ordered his soldiers if the French army fought back, they must retreated at once. However, the French government did nothing to face Hitler's provocation, and the Britain government did the same.
Thus, the most intensive time in Hitler's life had passed, which improved his first big move to challenge the Treaty of Versailles succeeded. Britain and France were trying that on the road to the war, they did anything they could to prevent it. At the same time, they wanted to minimize the damage and save their people's lives.
On March, 13th, 1938, Austria combined with Germany, which again broke the Treaty of Versailles. Actually Germany wasn't prepared for any battles, and 70% of its cars broke down on the road. Hitler got a clear view of this whole appeasement idea through the method and result of this combination, which was an important step to World War Two. The whole process of occupying Austria was so successful that Hitler himself was also influenced by the 'victory'. After this, Hitler wouldn't let go...