Morane-Saulnier M.S.406

When Germany attacked in May 1940, the most numerous fighter in the Armée de l’Air was the Morane-Saulnier M.S.406. It was not the best French fighter — the D.520 was, and barely three hundred of those had been delivered — but it was the one that existed in quantity, equipping the majority of France’s fighter groups.

It was not a new design. The M.S.405 prototype first flew on 8 August 1935, and the production 406 reached squadrons in early 1939; about 1,176 were built. By May 1940 that timeline was the problem: an aircraft drawn to a mid-1930s requirement was being asked to fight the fighters of 1940.

The M.S.406 was built around the Hispano-Suiza 12Y-31, a V12 giving 830 hp at take-off and 860 hp at 3,150 m. That drove it to 483 km/h at 4,000 m, and about 490 km/h at 4,500 m. It had a retractable radiator under the fuselage and, by common account, no vicious handling traits: pilots found it pleasant to fly and manoeuvrable.

Its armament followed the French pattern the D.520 would inherit — a 20 mm Hispano-Suiza HS.404 firing through the propeller hub with 60 rounds, and two 7.5 mm MAC 1934 machine guns, one per wing with 300 rounds each. On paper the hub cannon was a serious weapon. In practice the guns jammed frequently and responded slowly, and sixty rounds allowed for few mistakes.

Against the Bf 109E the decisive figure is a single one: the German fighter was 100 km/h faster. Manoeuvrability does not compensate for that margin, because speed hands the enemy the choice of whether to fight at all. The M.S.406 could not catch a 109 that wanted to leave, and could not decline combat with one that wanted to engage.

The list of secondary faults is long and specific: no armour protection, frequent gun jamming, inadequate firepower, slow gun response, unreliable radios, a very high rate of engine wear, corrosion in the rudder components, cabin glazing that broke under air pressure in some manoeuvres, exterior panels lost as their screws deteriorated, and no rear-view mirrors. Each is minor on its own; together they describe an aircraft that had reached the front without being developed.

The record of the Battle of France is stark. M.S.406 squadrons claimed 191 confirmed victories and 83 probables. Around 400 Moranes were lost: roughly 150 to enemy fighters and ground fire, about 100 destroyed on the ground in air raids, and the remainder deliberately destroyed by their own side to prevent capture.

One engagement shows the pattern. On 15 May, nine Moranes of GC III/7 met a dozen Bf 109s: three M.S.406 went down in flames, and further aircraft were lost or damaged, before any German fighter was claimed. The type holds the distinction of being the least effective French fighter in service during the campaign, an assessment attributed principally to its low firepower.

The same aircraft then produced the opposite result. Finland received 76 M.S.406s and 11 M.S.410s and flew them against the Soviet air force from the Winter War onward. Between November 1939 and 4 September 1944, the Finnish squadron LeLv 28 claimed 118 aerial victories on the Morane against the loss of 15 aircraft.

The contrast is not a matter of interpretation. In French hands: roughly 191 victories against some 400 losses, in six weeks. In Finnish hands: 118 against 15, over nearly five years. The airframe was identical. What differed was the opponent, the tactics, the tempo of the fighting, and the condition of the air force flying it.

Finland then addressed the aircraft’s central defect directly. Fitting captured Soviet Klimov M-105P engines — themselves a licensed development of the same Hispano-Suiza 12Y — rated at 1,100 hp, along with four belt-fed guns and the German 20 mm MG 151/20, produced the Mörkö-Morane. Speed rose to 525 km/h and the service ceiling from 10,000 m to 12,000 m.

Switzerland reached the same conclusion independently, building the type under licence: 84 D-3800s and 207 D-3801s, the latter with a 1,060 hp engine and a top speed of 534 km/h. Swiss examples remained in service as trainers and target tugs until 1959. Turkey took 45 aircraft and Croatia 48. Both re-engined versions point the same way: with roughly two hundred more horsepower, the Morane was competitive.

The M.S.406 was underpowered and under-armed for the war it met. It was pleasant to fly, well liked by its pilots, and comprehensively outpaced by the Bf 109E. France sent it into the decisive battle of its history as the mainstay of the fighter force because there was nothing else in sufficient numbers: the D.520 had been declared combat-ready only a month before the German offensive opened.

The aircraft’s own later record qualifies the verdict. Re-engined by Finland it reached 525 km/h; built under licence in Switzerland it reached 534 km/h and stayed in service until 1959. In France in 1940 it lost roughly two aircraft for every one it shot down; in Finland it claimed roughly eight for every one lost. On the evidence of the Finnish and Swiss conversions, the limits of the design were set by the engine it was given rather than by the airframe itself.

• William Green, Warplanes of the Second World War (Macdonald).
• Christopher Shores, Brian Cull & Nicola Malizia, Fledgling Eagles: Air Operations during the Phoney War and the Battle of France, 1940 (Grub Street).
• Barry Ketley, French Aces of World War 2 (Osprey, Aircraft of the Aces).
• Bill Gunston, The Illustrated Encyclopedia of Combat Aircraft of World War II (Salamander Books).