The United States Army created a large number of notional deception formations that were used in a number of World War II deception operations. The most notable fictional US formation was the First U.S. Army Group (FUSAG); this field army was originally intended as the main invasion force for the Invasion of Normandy, however that was renamed to the 12th Army Group. FUSAG remained in existence on paper and was used during Operation Fortitude South to divert Axis attention to the Pas de Calais area.

First United States Army Group was a fictitious Allied Army Group in World War II prior to D-Day, part of Operation Quicksilver, created to deceive the Germans about where the Allies would land in France. To attract Axis attention, prominent US general George S. Patton was placed in command of the fabricated formation.