Dummy M4 Sherman tank of the type used by the Ghost Army. It weighed 93 pounds fully inflated.

Dummy M4 Sherman tank of the type used by the Ghost Army. It weighed 93 pounds fully inflated. (Credits: National Archives)

Dummy M4 Sherman tank of the type used by the Ghost Army. It weighed 93 pounds fully inflated. (Credits: National Archives / Princeton Architectural Press)