 Allied bombing destroyed the majority of the historical Hanseatic city as well as 60% of the built up area of Bremen during World War II.The British 3rd Infantry Division under General Whistler captured Bremen in late April 1945.In 1946 Bremen's mayor Wilhelm Kaisen (SPD) travelled to the U.S. to re-establish Bremen's statehood, as Bremen had traditionally been a city-state, in order to prevent its incorporation into the state of Lower Saxony in the British zone of occupation.