United States Army General. His command assignments included Battalion Commander, 2nd Battalion, 60th Infantry Regiment, 9th Infantry Division, Vietnam from 1968 to 1969, Commanding General, 2nd Brigade, 101st Airborne Division, Fort Campbell, Kentucky in 1975, Commanding General, 3rd Infantry Division, Federal Republic of Germany from 1981 to 1983, Commander-in-Chief, United States Readiness Command, McDill Air Force Base, Florida from 1985 to 1986. In addition his army career included stints as Division Operations Officer of the 101st Airborne, Assistant Commandant of the United States Army Infantry School, Deputy Commanding General of the Combined Arms Combat Development Activity and Army Deputy Chief of Staff for Operations and Plans. He was posthumously inducted into the United States Army Ranger Hall of Fame and the building serving as the headquarters for the 3rd Infantry Division was named in his honor on May 16, 1989. He also was posthumously inducted into the University of Denver Athletic Hall of Fame as a heritage era inductee who was a two sport athlete, a All America and All First Team Sky Conference halfback, he still holds the school records for rushing yards, touchdowns and points for a single year in addition to being a track star. The Arlington National Cemetery website has the following notation, "While the Deputy Chief of Staff for Operations for the Army, General Mahaffy was instrumental in the reactivation of the 3rd Ranger Battalion and the 75th Ranger Regiment." He held a business degree from the University of Denver, a masters degree in international affairs from George Washington University and was a graduate of the Army Command and General Staff College and the National War College. He retired from the army on Oct 3, 1986 for medical reasons after a 6 month long battle with cancer. During his 31 year army career starting with ROTC at the University of Denver, he rose to the rank of four star general at the age of 51 and among his commendations are the Silver Star with two oak leaf clusters, the Distinguished Flying Cross with one oak leaf cluster, the Bronze Star for valor with 3 oak leaf clusters, the Distinguished Service Medal with one oak leaf cluster and the Legion of Merit officer degree with 3 oak leaf clusters.