Why did George S. Patton not command Allied ground forces during the Normandy Invasion?

George S. Patton did not command Allied ground forces during the Normandy Invasion for two primary reasons:

• Controversial Conduct: In August 1943, Patton physically struck two hospitalized soldiers suffering from combat fatigue in Sicily. These incidents, which were widely reported in the press, caused a public uproar and led many in the U.S. Congress to call for his dismissal. While he kept his job, these controversies likely cost him a command role in the Normandy operation.1
• Strategic Deception: Prior to the invasion, Patton was publicly placed in command of the First U.S. Army Group (FUSAG), a fictitious army used in Operation Fortitude. Because Patton was highly respected and feared by the German high command, his involvement gave the deception operation—which aimed to convince the Germans that the invasion would occur at the Pas-de-Calais rather than Normandy—considerable credibility.23