Sherman DD Tank- Duplex Drive M4A2(75). DD tanks worked by erecting a ‘flotation screen’ around the tank, which enabled it to float. The Sherman tank had two propellers powered by the tank’s engine for propulsion in the water. The DD tank would leave a vessel near the coast and support the infantry on the beaches. The 75 in M4A2(75) refers to the 75mm gun. Photographed at The Tank Museum in Bovington, England 2017.