After college, he enlisted in the U.S. Army in 1940 and was assigned to the 92nd Infantry Division as a forward observer.
On December 26, 1944, the Italian village he was at (Sommocolonia) was overrun by enemy soldiers. Lieutenant Fox earned a medal of honor for directing artillery fire on his position after he was overrun. His actions allowed allied forces to retake the village.
In addition to winning the Congressional Medal of Honor, Hasbro toy company has made a GI Joe commemorative action figure in his honor.