In what year did the Japanese "Zero" go into production?
Zero, also called Mitsubishi A6M or Navy Type 0, fighter aircraft, a single-seat, low-wing monoplane used with great effect by the Japanese during World War II. Designed by Horikoshi Jiro, it was the first carrier-based fighter capable of besting its land-based opponents. It was designed to specifications written in 1937, was first tested in 1939, and was placed in production and in operation in China in 1940.
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