During World War II, Americans of many different backgrounds and experience sets were drafted into the armed forces. One unit in particular, the 23rd Headquarters Special Troops of the U.S. Army, had an odd membership, made up mostly of artists, architects, designers, sound engineers, and other creative types — all of whom had to have an IQ of at least 119. And while other units were given standard issue weapons and benefited from the employ of tanks and artillery, the 23rd was given a much different order:

Fake it.

Sun Tzu, in The Art of War, famously observed that “all warfare is based on deception.” The U.S. military, via, the 23rd, took that literally. Using inflatable jeeps and tanks (such as the one pictured above), the 23rd was charged with convincing German troops that Allied firepower and numbers were greater than they truly were. The 23rd, known colloquially as the “Ghost Army,” would set up faux, inflatable battalions near German encampments (but away from the actual Allied forces) in hopes of convincing the enemy of plans which did not exist. These actors-as-soldiers would don different uniforms and insignias, with the hope of catching the eye of German intelligence — who, in turn, would report back (incorrect) estimates of manpower and location of Allied troops. And they even went with some high-tech subterfuge: according to NPR, the Ghost Army “mounted huge speakers onto trucks to project the sound of the recordings — such as troop or tank movement or the construction of a bridge.”

Their efforts were reportedly successful. For example, the 23rd set up a fake “mulberry harbor” — an artificial military harbor used to offload cargo and troops onto beaches, such as at Normandy a few weeks after D-Day — diverting German attention away from the true landing locations. But the biggest success? The Washington Post noted that at times, the Ghost Army convinced German adversaries that they numbered as many as 30,000 troops, even convincing some units to surrender out of fear of being greatly outmatched.

The U.S. Army may have used the tactic in other wars, as well, as the Ghost Army’s mission in World War II was kept classified until 1996 — and even today, many details are still kept secret.

Bonus fact : Don’t try the above at home — not because it’s dangerous, but because it’s incredibly expensive. An inflatable replica U.S. Army tank runs about $25,000. And while a dozen of them are clearly cost-prohibitive, they’re still cheaper than the real tanks, which run between $4 million and $6 million each.

From the Archives: Tanks for the Info: German tanks fell prey to another Allied weapon: math.

Related Reading: “Ghost Army of World War II” – a 280 page hardcover book exploring the Ghost Army, written by veteran reporter Jack M. Kneece in 2001.