First United States Army Group

Fictitious WWII Allied military unit
the oldest and longest established field army of the United States Army

First United States Army Group (often abbreviated FUSAG) was a fictitious (paper command) 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.

First U. S. Army Group was activated in London in 1943 as the planning formation for the Allied invasion of France under General Omar Bradley. When Twelfth United States Army Group was activated on 1 August 1944, Bradley and his staff transferred to the headquarters of the new army group. Despite a lack of personnel, FUSAG continued to exist on paper as part of the deception of Operation Quicksilver. In order to make the German forces believe the Allied invasion would come at Pas de Calais, the phantom force was stationed at Dover, directly across the English Channel from the site. To further attract the Axis commanders' attention, General Dwight D. Eisenhower placed George S. Patton in command of the phantom force and increased the formation's apparent size to be larger than the British led 21st Army Group under Bernard Montgomery. Patton was considered by the Germans to be a formidable offensive commander; he was temporarily unemployed as punishment for slapping a battle fatigued soldier in Sicily. The deception worked so well that significant German forces remained in the Pas de Calais region for seven weeks after the real invasion at Normandy to defend against what they thought would be the true invasion force. Agents infiltrated by Germany into the United Kingdom who became double agents acting for Britain in the Double Cross System—notably Juan Pujol García (Garbo)—played a vital role in persuading the Germans that FUSAG was real. After it had become clear that Normandy, not Calais, was the invasion site, to preserve the credibility of the Double Cross network's agents in spite of the totally false information they had persuaded the Germans to believe, the Germans were persuaded that FUSAG had been real, but had been disbanded and attached to the forces at Normandy because the Normandy "diversion" had been so successful that the Calais landing had become unnecessary.