guns or carrier-based fighters. The lightweight structure and complete lack of defensive machine guns and the additional crew necessary to operate them (features in the early prototype design) were considered essential to maintain the speed and high-altitude performance of the G3M with a heavy payload. Even after the modified final prototype, which did include three defensive machine gun emplacements, the G3M kept its lightweight structure and lacked any form of defensive armour or self-sealing fuel tanks, as these were considered to retard speed and altitude. This trait in Japanese bomber and fighter design manifested itself again in its successor, the Mitsubishi G4M, whose design so strongly emphasized fuel and bomb load for long-range strikes at the expense of defence that its vulnerability to fighters and ground and surface gunfire earned it the unofficial nickname of "one shot lighter" by Allied fighter pilots. The bombsight used in the G3M was primitive compared to the mechanisms used in the G3M's contemporaries such as the B-17 Flying Fortress and Heinkel He 111. Aside from the limited precision necessary in its naval role as a long-range torpedo bomber against Allied naval fleets, the G3M frequently operated with other G3M units in massive "wave" formation. Use of these large formations eliminated the need for singular high-precision bombing attacks. Later the Nakajima Company redesigned the G3M into the improved G3M3 (Model 23) with more powerful engines and increased fuel capacity. This version was manufactured only by Nakajima, being the most rapidly produced in wartime. This version entered service in 1941, and was maintained in service for two years, and later used in 1943 alongside the G3M2 for long-range maritime reconnaissance with radar, due to its excellent long-range performance. Other G3M derivations were the transport versions, G3M-L and L3Y, the latter built by Yokosuka. Operational history The G3M flew for first time in 1935, taking off from a Nagasaki airfield belonging to Mitsubishi Heavy Industries and landing at Haneda Airport on the outskirts of Tokyo. The G3M first saw combat in Japan's expansionist campaigns on the Chinese mainland in what became known as the "Second Sino-Japanese War", where the G3M was able to exploit its long-range capability when, during August–November 1937, the 1. Rengo Kōkūtai (a special unit) was established, operating alongside the Kanoya and Kizarazu Kōkūtai based in Taipei, Formosa, Omura, Kyūshū and Jeju Island. On 14 August of that same year, 42 G3Ms and seven