At the beginning of the Second World War, due to the lack of effective attack weapons and the inability to accurately locate submarines, the Allied planes were helpless in the face of German submarines. In order to win, it is necessary to modify the bomb, and at the same time, it is necessary to add bombing sights and new detection instruments. But it takes at least two years to equip a brand-new weapon from development to perfection and mass production. Therefore, refitting an original weapon to meet the urgent need has become the first choice.

At that time, the only airborne anti-submarine weapon that could be found in Britain was a 450-pound cylindrical anti-submarine bomb. Based on this bomb, the British army made a weapon for the temporary use of anti-submarine aircraft in the spring of 1940, which is the ⅶ-type deep-water bomb. This kind of bomb has a circular fairing at the warhead and a tail wing at the tail, and its attitude in the air is very stable.