The M4 was a development of the General Grant supplied to the British by the US under Lease-Lend. British tanks carried the 2-pounder and the desert army was frustrated by Germans’ use of anti-tank guns which they could not engage without HE. A new tank was proposed. It became the M4 Medium – to the British, the Sherman – the best-known tank of WWII. It was produced in prodigious numbers – over 50,000 of one type or another. The first models were delivered to the Eighth Army in time for the second battle of Alamein then served in every theatre of the war with nearly every armoured formation of every country on the Allied side. But the Sherman was no match for the German Panther. The British War Office insisted that some Sherman IIs and Vs were fitted with the British 17-pounder gun in time for the Allied invasion of Europe. This development was known as the Sherman ‘Firefly’. Although the extra length of the barrel posed something of a problem in close country like the Bocage, the modification made it possible for Allied units to engage Panther and Tiger tanks with some degree of equality. In addition to its normal uses the Sherman chassis was used as a mount for several special-purpose vehicles, such as the Crab mine-sweeping tank, anti-aircraft tank, armoured personnel carrier, and tank destroyer. Large numbers were converted for amphibious use and ‘swam’ ashore during the D-Day invasion of Europe.