Lioré et Olivier LeO 45
The Lioré et Olivier LeO 45 was a French twin-engined medium bomber designed to a 1934 requirement and first flown in January 1937. Its production version, the LeO 451 with Gnome-Rhône radial engines, was France's best medium bomber of 1940 but reached front-line units too slowly to affect the Battle of France. The type went on to serve Vichy France, the Free French, Germany and Italy, was built in two separate production runs either side of the 1940 armistice, and ended its career in post-war test and transport conversions, the last examples retiring in 1957.
Why It Mattered
The LeO 451 was the strongest medium bomber France took into the Battle of France — History of War calls it the best in French service — but it arrived in numbers too small to change the result. The design answered a November 1934 requirement for a five-seat bomber, then a demanding specification for its time. Production could not keep pace with the need: when the German offensive opened on 10 May 1940, front-line units held 94 of the aircraft and only 54 were fit to fly. The type's career still ran far beyond the defeat, through Vichy and Free French service and a post-war life that ended only in 1957.
Design Notes
Lioré et Olivier answered the requirement with a streamlined twin-engined monoplane of all-metal construction, fabric covering only the control surfaces. The prototype flew on 16 January 1937 behind Hispano-Suiza engines, but they overheated, and in August 1938 the design was re-engined with Gnome-Rhône 14N radials; the revised prototype, as the LeO 451.01, began its flight tests on 21 October 1938. Defensive armament centred on a retractable dorsal turret with a 20 mm Hispano-Suiza cannon, and the twin fins were shaped in part to clear that gun's field of fire. Bombs went in three internal bays. Production aircraft lost a little speed when a shortage of Gnome-Rhône propellers forced the switch to Ratier airscrews, the top speed falling from 311 to 298 mph.
Operational History
The first production LeO 451 flew on 24 March 1939, yet deliveries crawled: on 3 September 1939 the air force had ten aircraft on charge, although 22 had been delivered. In all, 449 had been completed when the armistice stopped production — some sources say 452 — against 1,548 ordered. The first combat sortie came on 11 May 1940, a low-level attack by ten aircraft on German columns in Belgium; one was shot down and the nine that returned were all heavily damaged by ground fire. Losses stayed severe — nine of twenty aircraft sent against positions around Amiens and Abbeville on 31 May were lost — and by the armistice France had lost 130 LeO 451s to all causes. Vichy kept the type flying: four groups bombed Gibraltar in September 1940 in reprisal for the Allied attack on Dakar, and three groups fought in Syria in the summer of 1941, losing 28 aircraft there. Production even restarted under Vichy, with 225 new aircraft ordered in August 1941, and the fleet reached 270 aircraft by October 1942. After the Allied landings in North Africa the surviving French aircraft changed sides; in early 1943 three groups flew 80 sorties against German targets in Tunisia before the type was replaced by Halifaxes and Marauders. Germany had seized 94 aircraft after occupying Vichy France, keeping 28 as fast transports and liaison aircraft and giving 66 to Italy.
Afterlife
At least 67 LeO 451s survived the war, 45 in North Africa and 22 in France, most of them in poor condition; most were refurbished. Eleven became LeO 451E flying test beds, used mainly for weapons trials, and three were converted into LeO 455s to test the Gnome-Rhône 14R engine. Five more were modified as LeO 455Ph photographic aircraft for the Institut Géographique National. The biggest second career belonged to the LeO 453, forty aircraft re-engined with Pratt & Whitney engines as high-speed transports and search-and-rescue aircraft. That version stayed in service until 1957, and when the last of the type was retired in September 1957, the LeO 451 was the last pre-war French design to leave active duty.