Japan’s naval treaties of the era limited its carrier and battleship tonnage, so the Navy looked for another way to project power across the vast distances of the Pacific. The answer, pushed hard by then-Rear Admiral Isoroku Yamamoto in the Naval Aviation Department, was a shore-based bomber whose reach would let a handful of airfields cover great stretches of ocean. The 1934 specification asked for range far beyond anything then normal for a twin.

Mitsubishi’s engineers, led by Kiro Honjo, achieved it by wrapping a very slim fuselage around a long, efficient wing and accepting light structure and modest defensive armament as the price of endurance. The result was fast and far-reaching for 1936, but the same choices — thin skin, no self-sealing tanks, few guns — would later make the G3M and its Betty successor dangerously vulnerable once they met modern fighters and massed anti-aircraft fire.

On 14 August 1937, days after fighting flared at Shanghai, G3M units launched what are widely regarded as the first trans-oceanic bombing raids in history. The Kanoya Air Group flew from Taihoku (Taipei) on Formosa and the Kisarazu Air Group from Omura in Kyushu, crossing hundreds of kilometres of the East China Sea to strike Shanghai, Hangzhou and Nanking. No aircraft had ever mounted sustained strategic strikes across so much open water.

The raids proved the range concept spectacularly — and exposed its flaw just as sharply. Flying without fighter escort, the Nells were mauled by Chinese pilots, with the two groups reportedly losing something like 40 per cent of their strength within about two weeks. It was one of the earliest demonstrations that even fast, long-ranged bombers needed escorts, a lesson every air force would relearn the hard way over the next decade.

On 10 December 1941 the British battleship Prince of Wales and battlecruiser Repulse — the core of “Force Z” — were caught off the Malayan coast near Kuantan with no air cover. Land-based bombers of the 22nd Air Flotilla struck in waves: G3M level-bombers and torpedo bombers of the Genzan and Mihoro air groups, joined by G4M torpedo bombers of the Kanoya group, roughly 85 aircraft in all, of which about 59 were G3M Nells.

In a running attack of about two hours the two ships were hit by multiple torpedoes and sunk, for the loss of only three or four Japanese aircraft. It was the first time capital ships free to manoeuvre and defend themselves on the open sea had been sunk purely by air attack — a result that stunned the Royal Navy and confirmed that the battleship no longer ruled the ocean. The G3M, a design already five years old, was at the centre of it.

There is no credible unit cost or cost-per-flight-hour figure for the G3M in the public record. It was a wartime product of the Imperial Japanese Navy, procured through the Navy’s own arsenal-and-contractor system rather than sold on any open market; contemporary yen pricing was not published, and a great deal of Japanese industrial documentation was destroyed in 1945.

Any specific dollar or yen figure attached to a G3M online should be treated as unverified. Production figures are firmer but still vary between sources: roughly 1,048 aircraft were built in total, the great majority by Mitsubishi with a substantial batch by Nakajima, though the exact manufacturer split differs from reference to reference and should be read as an estimate.