The 1.59-inch Breech-Loading Vickers Q.F. Gun, Mk II was a British light artillery piece designed during World War I. Originally intended for use in trench warfare, it was instead tested for air-to-air and air-to-ground use by aircraft. Although it fired shells and had no capability to launch rockets, it was widely but misleadingly known as the "Vickers-Crayford rocket gun."