During World War Two the Allies and Germans both used many kinds of tactics to fool the enemy, creating false radio transmissions and placing decoys that looked like groups of tanks and trucks, so when the enemy went there they found nothing and wasted their time, or used up bombs on worthless decoys.
On the other hand, sometimes an actual tank would be disguised as a far less valuable asset, as is the case this tank in North Africa that been fitted with an artificial cover to make it look like a relatively worthless utility truck and allowing a surreptitious build of of tanks in the area.
