The Leyland Hippo Mk II was a new design by Leyland, developed as a result of the planning for D-Day, which concluded that trucks with 10 long tons (10 t) cargo capacity offered considerable logistic advantages over smaller vehicles. Design of the Hippo Mk II commenced in 1943 with production commencing in late 1944. The Hippo Mk II arrived too late to see service in the days immediately after D-Day, but roughly 1,000 were in service by VE Day and they remained in service with the British Army and the Royal Air Force into the 1950s.