The M4 Sherman tank was a centerpiece of Allied armor throughout the Second World War, and many variants were produced to meet battleground requirements. It was rugged, unsophisticated, and perfectly suited for mass production and more than 50,000 units were produced. The M4A3E2 variant known as "Jumbo" was produced in 1944 to meet the requirements for a heavily armored assault tank capable of close infantry support during the coming battles. Armor protection was improved by welding an additional 38mm rolled armor over the hull front and side sponsons, increasing total thickness to 101mm and 76mm respectively. The new cast turret had an all around wall thickness of 152mm, and mounted a 75mm M3 gun, ideal for infantry support roles. Although powered by the powerful Ford V8 cylinder, liquid cooled, 500hp engine, the additional armor translated to a hefty 38.1 tons of vehicle weight, resulting in alteration of the final drive ratio to insure satisfactory performance in the field. To better its maneuverability in traversing soft terrain, extended end connectors for the tracks, called duckbills, were added a shte need arose. Production of the M4A3E2 began at the Fisher Tank Arsenal in May 1944, with 254 units begining delevered by July. It first appeared in an operation at St. Lo, France in July the same year