Designed by Willy Messerschmitt during 1934, and originally powered by a Rolls-Royce Kestrel V engine, the Me109 won a fighter competition in October 1935. During the process of progressive development in the pre-war years the aircraft appeared in successively more powerful and heavier armed versions; and the Me109B and C models achieved great success in Spain with the Legion Condor's fighter unit. Many of the Lufwaffe's most successful wartime fighter pilots received their operational blooding in Spain on the early 109 models. By August 1940 twenty-three Gruppen were in action on the Channel front mainly equipped with the improved Me109E-3 which mounted two machine guns in the nose, and two in the wings. Provision for a cannon firing through the spinner was also made in the design, but due to heating and vibration problems, this was never used in action.