Walter Moon was born on March 31, 1923, in Rudy, Arkansas. He enlisted in the U.S. Army on June 6, 1944, and after seeing combat in Italy, he received an honorable discharge on July 17, 1946. He then attended the University of Arkansas, and was commissioned a 2d Lt of Infantry through the Army ROTC program there on June 1, 1950. After completing Infantry Officer training at Fort Benning, Georgia, Lt Moon served with the 4th Infantry Division in West Germany from June 1951 to June 1954, followed by service as Professor of Military Science and Tactics with the Army JROTC Program at Savannah High and Commercial High Schools in Savannah, Georgia, from June 1954 to June 1957. Capt Moon attended Advanced Infantry training at Fort Benning from June 1957 to June 1958, and then served as Aide to the Deputy Commander of Eighth Army in South Korea from June 1958 to June 1959. His next assignment was with the 1st Special Forces Group at Fort Bragg, North Carolina, from June 1959 until deploying to Southeast Asia in early 1961. He was captured and taken as a Prisoner of War in Laos while serving as an advisor with the 7th Special Forces Group, Military Advisory and Assistance Group Laos, on April 22, 1961. After an escape attempt, Maj Moon was executed by his captors on July 22, 1961. His remains have never been returned to the United States.

His Silver Star Citation reads:

Major Walter H. Moon, Infantry (then Captain), United States Army, distinguished himself by gallantry in action while engaged in military operations during the period April 1961 to July 1961. Major Moon was serving in an advisory capacity in Laos when he was captured by hostile forces. From the initial time of his capture, he was kept in solitary confinement and subjected to extreme mistreatment, abuse and vile physical environment. Despite the never-ending brutalities, he constantly demonstrated boldness, tenacity, and courage by his continuous overt actions against his captors. Although faced with insurmountable odds, he repeatedly attempted to escape and was seriously wounded during his first break for freedom. From the time of his first attempt to escape until his death, he refused to collaborate with, and resisted the cruel efforts of his captors and prevented their making propaganda capital at the expense of the United States. Wounded, and weakened physically, Major Moon fought with the guards inflicting as much bodily harm on them as possible, until he was completely overpowered and mortally wounded. Major Moon's intrepid conduct, aggressive actions and self-sacrifice are in keeping with the highest traditions of the United States Army and reflect great credit upon himself and the military service.