 Arguably the best light anti-aircraft gun of the Second World War, the 40 mm Bofors was used for air defense both on land and at sea by many of the countries involved, including the Americans, British, Dutch, Japanese, and Swedish. Produced in the early 1930s, it first entered service with the Royal Netherlands Navy when the cruisers Java and Sumatra were refitted in 1934 – 35. Before the Second World War, Hazemeyer, a Dutch subsidiary of the German company Siemens & Halske, had devised "a very advanced triaxial mounting together with a tachymetric control system" for the 40 mm gun. When the Netherlands fell in 1940, this was brought to the U.K. aboard the minesweeper Willem van der Zaan, where it was copied and put into service as the British Mark IV twin mount. The description of the proposed fire control mechanism for the 1047s, discussed on 6 November 1939, mentions that the 40 mm weapons were "to be controlled autonomously from the gun positions"; this seems to describe Hazemeyer's system, but no direct link is made in sources.
