18,000 B-24 Liberators were produced making it the most widely produced US heavy bomber of WWII. It gained a distinguished war record with its operations in all theatres. The Liberator VI was the RAF designation for the B-24H and early B-24Js, the first production versions of the aircraft to be built with a nose turret which was the most numerous RAF version with over 1,100 being delivered. Coastal Command used a slightly modified version very successfully against the U-Boat threat in the North Atlantic.