Often outclassed against enemy fighters in French service, the MS406 was a more potent opponent when improved in Finnish hands

The first unit to get its hands on the Morane- Saulnier monoplane fighter, albeit in early pre-series MS405 form for operational evaluation only, was the 4th Escadrille of Groupe de Chasse (GC) II/7 at Dijon in the summer of 1938. Although the MS405s suffered minor teething troubles, the Groupe II pilots found France’s first modern fighter vastly superior to the Blériot SPAD 510 biplane flown by the rest of the unit. Early-build MS406s followed in September 1938, allowing the 6th and 7th Escadres de Chasse to begin their conversions in early 1939.