The Navy was segregated and Black sailors were usually assigned menial work such as stevedores.[157] At Port Chicago on 17 July 1944, while mostly Black stevedores were loading up two Navy supply ships, an explosion occurred that killed 320 men, of which 202 were Black.[158] The explosion was widely blamed on the lack of training for Black stevedores, and 50 of the survivors of the explosion refused an order to return to work, demanding safety training first.[159] At the subsequent court martial for the "Port Chicago 50" on the charges of mutiny, their defense lawyer, Thurgood Marshall stated: "Negroes in the Navy don't mind loading ammunition.