 When Philipp was arrested in September 1943 on suspicion of plotting with the Italian royal family to overthrow Mussolini, the palace was plastered with posters denouncing the Italian royalty.The palace survived Allied bombing raids during World War II (1939-1945) with little damage.The palace was acquired by the city of Kassel in 1956, and until 1970 it was the home of the Municipal Art Collection.