The U.S. Navy Armed Guard was the division of the U.S. Navy responsible for protecting merchant vessels from submarine and aircraft attacks. Armament on merchant vessels began with one gun in World War I and increased in World War II to two large guns, either 3-inch, 4-inch, or 5-inch, and six to eight 20 mm guns. A cargo ship's Navy gun crew consisted of a commanding officer, radiomen, signalmen, and gunners, and these selected men received intense, thorough, and demanding training. The combination of armament and specially trained men stopped attacks on merchant vessels. By the end of World War II, the Armed Guard, with personnel totaling 144,970, was protecting more than 6,236 ships. Losses due to enemy action were 1,810 men killed, 27 taken prisoner, and 19,880 men who survived 710 torpedoed ships. The Armed Guard was a major factor in winning World War II.
