A Ghost Army trooper paints an inflatable rubber tank modelled on an M-4 Sherman. The 23rd Headquarters Special Troops, an elite force whose speciality was tactical deception, was a matter of military secrecy until its declassification in 1996.

Military deception is as old as war itself, but the idea the Allied planners came up with represented something new: a mobile, self-contained deception unit capable of staging multimedia illusions on demand. The 1,100 men in the unit were capable of simulating two full divisions—up to 30,000 men—with all the tanks and artillery that the real units might be expected to have. The illusion might discourage the enemy from exploiting a weak spot by making the site seem as if it was heavily defended, or could draw enemy troops away from where real American units were planning an attack.