After coming to power, Hitler took several aggressive foreign policy actions which Britain and France failed to stop. He annexed Austria in 1938 and was allowed to take the Sudetenland region of Czechoslovakia under the Munich Agreement, despite promising it would be his last territorial demand. In 1939, Hitler seized the rest of Czechoslovakia. Britain and France had pursued a policy of appeasement but Winston Churchill strongly opposed this, warning that it would lead to war. Germany then invaded Poland using lightning-fast Blitzkrieg tactics, and the war began.