LeO 45 was a French medium bomber used during World War II. The LeO 451 was conceived as a second-generation strategic bomber for the new French Air Force. In contrast to its predecessors which relied on machine guns for protection, the emphasis was placed on high-speed high-altitude cruise.
The first production LeO 451 was built in 1938. At the start of the Battle of France on 1940-05-10, only 54 of the 222 LeO 451 were considered ready for combat, the remainder being used for training, spares, or undergoing modifications and repairs. Following the Armistice, LeO 451s continued to fly, now under the Vichy government, that used them during the Syria-Lebanon Campaign. Following the war, the 67 surviving aircraft were mostly used as trainers and transports. The LeO 451 was finally retired in September 1957, making it the last pre-war French design to leave active duty.