The 100 mm gun was the standard weapon of destroyers and other small craft during the First World War. In 1925 it was decided to upgrade the weapon to a length of 45 calibres. Five models of this weapon were produced and placed in service, the sixth model was developed but was not used. This gun equipped submarines, destroyers, treaty cruisers and battleships. As a 45 calibre weapon it would remain in service until the end of the Second World War.