When playing poker, a bluff is a completely logical strategy. You've got basically nothing and you're trying to pressure your opponent into thinking you've got them completely beat via pure posturing. In a time of war, when both sides employ hundreds of scouts, do near-constant aerial reconnaissance, and have spies constantly floating around the battlefield, bluffs shouldn't work.
You'd think that any soldier with a pair of binoculars would realize that something was amiss upon observing a bunch of plywood artillery cannons, tank-shaped balloons, cardboard cutouts of troops, and a couple commo guys messing around on the airwaves. And yet the 23rd Headquarters Special Troops, better known as the "Ghost Army," went on to fool the Nazis at every turn.
As the old Army saying goes, if it looks stupid, but works, it ain't stupid.
If you saw this from your cockpit for half a second and you had no idea your enemy was using inflatable tanks, you might fall for it, too.
The Ghost Army was inspired, in part, by British Field Marshal Bernard Montgomery's successful use of hoax tanks as part of Operation Bertram, but during Operation Quicksilver, Americans took things to the next level. British measures employed to successfully fool Axis onlookers were good, but the assets of the Ghost Army were exceedingly precise. Each inflatable tank took days to make, and they were so realistic that enemy reconnaissance couldn't tell the difference.
To help sell the illusion, radio guys blasted the sounds of tanks through loud speakers. This way, any onlooking Nazi scout would hear what sounded like an entire division of tanks rolling through the area, quickly glimpse the balloon tanks in the distance, and promptly run back to their commander to prepare for the impending "fight." The inflatable Sherman tanks weren't alone — they also employed wooden mock-ups of artillery guns in dugouts that would draw out enemy fire.
Visual deception was key, but another crucial task was sending out relevant radio transmissions in hopes that they'd be intercepted by the Germans. The illusion worked best when several types of deception worked in concert. The Nazi code-breaker would "intercept" a message about the 23rd moving to a certain point on the Rhine, the Luftwaffe would fly ahead and see the "tanks," and, if any Nazi scouts were to see soldiers of the 23rd, they'd likely see troops donning high-ranking officers uniforms — and this is exactly what the Ghost Army wanted them to see: a seemingly ripe target.
The 23rd drew the attention away from many key Allied movements, leaving the Germans easily flanked by the actual Army that came to fight. The Germans were too distracted by the Ghost Army to realize that the Americans started crossing the Ruhr River and, as a consequence, they arrived first at the Maginot Line many, many miles away from where the Americans would break through.
All thanks to a bunch of artists and jokers.
To learn more about the 23rd Headquarters Special Troops, check out the video below: