The cycle and motor manufacturing industries brought into existence a wide variety of subsidiary trades. Most notably these were general engineering, metal casting, drop forging, chain-making and the manufacture of instruments and gauges, machine tools, and all types of electrical equipment. The manufacture of aircraft, aero engines and related equipment also took place in Coventry as early as 1916, and during World War II the aircraft industry dwarfed all other local industries. With the outbreak of war many of the motor firms switched to aircraft work, and the whole of Coventry's industrial skills and resources turned to war production of one sort or another.