In 1907, the U.S. Navy summoned a board on the development of measures against threatening torpedo craft; this board summed up the problems then existing. Among the problems were a lack of sufficent firepower to stop enemy fast craft, and the problem of finding them in the first place, especially at night. The latter problem was temporarily solved with searchlights (although these were never used to the benefit of their employer, at least not in the U.S. Navy. The reason is that the searchlight must actually find something to help the searcher, but is always a aiming point for the ship to be found.), the former by the development of a high-velocity gun.

    This gun was the L/50, 127mm gun, which was replaced in service by the L/51. It was employed in battleships only (in all from the Florida class to the Marylands), but post 1941, when several of these guns had been taken off the damaged battleships, they were also used in submarines, merchants and auxilliaries, in old destroyers, coast guard cutters and coastal batteries.