In WW2, there was a secret 1100-man US Army unit dubbed the ‘Ghost Army’, which was made up of artists, creatives & engineers. Their job was to create deceptions – from inflatable tanks to scripted bar conversations, their work led to big Allied wins. – WTF Fun Facts
WTF Fun Fact – Ghost Army

It was actually used for D-Day because the Axis powers didn’t know where the invasion was going to be at so they sent the “ghost army” to a location so the Axis powers would think that was the attack then really attack at the actually location. Also a fun fact is they threw long strand of foil off of aircrafts to mess with German radar during D-Day