Steel rear driving sprocket, British Mark II tank : Bullecourt

Steel driving sprocket of bolted construction, with a central tube bearing and a circular toothed driving wheel on each side. Corrosion on all surfaces.

This is part of the remains of one of the dozen or so Mark II British tanks meant to support the Australian infantry (the 4th and 12th Brigades of the 4th Australian Division) at the First Battle of Bullecourt (10-11 April 1917). Their use was seized on by commander of the British 5th Army Sir Hubert Gough, in his rushed planning for the assault, in lieu of artillery. The tanks were meant to lead and protect the infantry in their assault on the heavily fortified village of Bullecourt which formed part of the Hindenburg Line; instead, seven broke down on their way to the starting line and the remainder were quickly knocked out, leaving the Australians exposed, without artillery support and the German wire entanglements unbroken. Despite capturing section of the German lines, they were forced to retire with 3,300 casualties, including over 1,100 taken prisoner.

This main toothed rear drive sprocket is one of two expected for a Mark II British tank. It was recovered from the Bullecourt area by local residents. The manufacturers for the Mark II series of tanks were either Foster & Co (which built 25 male tanks; or Metropolitan (which built 25 female versions).