A primary antiaircraft weapon used by Allied forces during the violent air and sea battles of World War II was the Mark 2 quadruple mounted 40 millimeter gun mount, or "Quad 40." Each individual Quad 40 gun was capable of firing shells weighting two pounds for a sustained rate of 160 rounds per minute-reaching ranges exceeding five nautical miles and almost four nautical miles in altitude. Weighing 24,900 pounds per mount, battleship Wisconsin once bristled with antiaircraft guns, including twenty Quad 40 emplacements for a total of eighty individual 40 millimeter gun barrels.
U.S. Navy battleships like Wisconsin were primarily used as heavily armored refueling and antiaircraft platforms supporting the fast-carrier task groups of the Pacific Fleet during World War Two. After 1942, antiaircraft gun mounts like the Quad 40 were added in response to the ferocious Imperial Japanese air and suicidal Kamikaze attacks of the Pacific campaign. Wisconsin was originally designed to accommodate a standard ship's complement of fewer than 1,550. With the additional antiaircraft emplacements, another 1,925 sailors were required to serve the guns. As a result, Wisconsin was quite cramped during the war with over 3,000 bluejackets living in every nook and cranny aboard ship.