During the late 1930s, there was a growing perception that a major conflict between Germany and France was not only looming but increasingly unavoidable. As part of preparatory measures, the French Air Force placed an order for 1,000 M.S406 airframes during March 1938. However, Morane-Saulnier was unable to produce anywhere near this number at their own factory, thus a second assembly line was established at the nationalized factories of SNCAO at St. Nazaire in order to produce the type. In April 1937, an initial order for 50 SNCAO-built M.S.406 fighters was placed; in August 1937, a follow-up order for 80 aircraft was issued. In April 1938, as a component of the French Air Force's "Plan V", a large order for 825 M.S.406 was placed with the various nationalised French aircraft industries.