Innumerable books have been published on the two most famous fighter aircraft of all time, the Supermarine Spitfire and the Messerschmitt Bf109. But books setting out to tell the story of both aircraft are very much rarer - probably fewer than the fingers of one hand. Yet their joint story is one which bears retelling since both were essential to the air campaigns of World War Two.Incredibly, the men who designed them lacked any experience of designing a modern fighter. R J Mitchell had begun his career working on industrial steam locomotives, Willy Messerschmitt had cut his aeronautical teeth on light and fragile gliders and sporting planes. Yet both men not only managed to devise aircraft which could hold their own in a world where other designs went from state-of-the-art to obsolete in a staggeringly short time, but their fighters remained competitive over six years of front-line combat. Despite the different ways their creators approached their daunting tasks and the obstacles each faced in acceptance by the services for which they were designed, they proved to be so closely matched that neither side gained a decisive advantage in a titanic struggle. Had either of them not matched up to its opponent so well, then the air war would have been a one-sided catastrophe ending in a quick defeat for the Allies or the Axis powers, and the course of twentieth century history would have been changed beyond recognition.