Britain's Contraband Control In Operation - Cutting Off Germany's War Supplies - The Chief Examination Officer (centre) giving instructions to Boarding Officers in the Central Control Room, Boarding Office. One of the Allies' most powerful weapons in the war against Germany is Britain's contraband control system, designed to out off from Germany her supplies of vital war materials. Control stations have been established on Britain's coasts, and cargoes and papers of neutral ships are carefully scrutinised with the minimum of delay. It has been announced that in the first month of the war, Britain secured for her own use 150,000 tons of merchandise more than the total lost by U-boat sinkings. October 4, 1939.