Britain and France guarantee Polish Sovereignty: 31 March 1939

After the occupation of Czechoslovakia by German troops 16 March 1939, the French and British governments offered a guarantee of Polish sovereignty against any act of aggression. The violation of the Munich agreement by Hitler had convinced the French and British governments that the policy of appeasement had not been effective, and that firm action must be taken to discourage Nazi Germany from making additional territorial demands in Europe. However, the German government initiated a new series of demands for the return of the Polish Corridor, German land that had been ceded to the new Polish state at the 1919 Paris Peace Conference.