[1][4] In November 1943, the 357th Fighter Group was assigned to European Theater of Operations and was stationed at RAF Leiston in England, where the unit was now equipped with the North American P-51 Mustangs.

On 25 July, he shot down a Bf 109 over Paris, France, his seventh aerial victory, before he returned back to the United States for shore leave.

He joined California Air National Guard and commanded a fighter wing, and worked as a public relations representative for North American Aviation.

On March 25, 1950, while flying a B-25 Mitchell converted for civilian use, from El Paso, Texas to Inglewood, California, he was killed with five other occupants when the aircraft broke up in mid-air over Gilbert, Arizona.

[3][18][19] The President of the United States of America, authorized by Act of Congress July 9, 1918, takes pleasure in presenting the Silver Star to Major (Air Corps) Robert William Foy, United States Army Air Forces, for gallantry in action against the enemy as a P-51 Fighter Pilot of the 363d Fighter Squadron, 357th Fighter Group, Eighth Air Force, in action against the enemy in aerial combat in the European Theater of Operations on 29 June 1944.

With extreme disregard for personal safety, he skillfully maneuvered the attacking aircraft within range of his one effective gun and shot it down in flames.

A few minutes later, when his remaining gun ceased to function, Major Foy pursued a Messerschmitt 109 with such tenacity the plane dived into the ground and exploded.