 Those that saw action included a bulldozer blade, the Duplex Drive system, flamethrowers for "Zippo" flame tanks, and various rocket launchers such as the T34 Calliope.British variants (DDs and mine flails) formed part of the group of specialized vehicles collectively known as "Hobart's Funnies" (after Percy Hobart, commander of the 79th Armoured Division).The M4 Sherman's basic chassis was used for all the sundry roles of a modern mechanized force.