Terry Dunn:

Few engines throughout history have achieved a near mythical status among its admirers. Fewer still can share credit for the rescue of an entire nation. Perhaps only the Rolls-Royce Merlin engine can claim both distinctions. During the Battle of Britain, it was the Merlin that powered the Royal Air Force Hurricanes and Spitfires that were England’s only effective defense against German air attacks. With the battle won, and the engine’s reputation thus established, the Merlin would become the stuff of legend and the powerplant of choice for numerous other aircraft.

Even before the 1940 air battles over England, it was apparent that demand for the Merlin was far outpacing Rolls-Royce’s ability to produce them. The Ford Motor Company was asked to build 9,000 Merlins for both England and the US. Ford initially accepted the deal, but later reneged. Henry Ford explained that he would only produce military items for US defense. Interestingly, Ford of Britain in Manchester, England ultimately produced 36,000 Merlin engines, beginning at the same time period. Of course, Ford’s American factories would indeed become vital to the war effort. They manufactured unfathomable quantities of airplanes, jeeps and other war materiel–but not Merlins.