Czechoslovakia began to fall apart after losing the Sudetenland to Germany. Poland and Hungary took parts of Czech territory while Germany occupied the rest in March 1939. Britain and France changed tactics and promised to defend Poland if it was attacked, questioning whether appeasement had been a mistake. Historians have differing views on appeasement, with some arguing it allowed Germany to make more demands while others believe it was necessary to avoid war while rearming from World War I.