Between 1941 and 1945, the USA supplied tens of thousands of its Medium Tank M4 to many of its Allies under the terms of the Lend-Lease Act. Britain received far more than any other nation (approximately 34% of the total output). In fact, it was the British who first dubbed the tank ‘Sherman’, continuing the practice of naming their US tanks after American Civil War generals. The US later adopted the name and proceeded to do likewise with future tanks. In the British naming system, the major variants were identified by Mark numbers: M4 became Sherman I, M4A1 became Sherman II, and so on.