He served from 1937 to 1960 in the Wyoming Army National Guard, where he became a colonel.

[2] He was in the 115th Cavalry Regiment and during the Korean War, he was the commander of the 300th Armored Field Artillery Battalion, known as the "Cowboy Cannoneers".

[2][3][4] While in Korea, the 300th Armored Field Artillery Battalion fought with distinction and earned the Distinguished Unit Citation.

[6] In 1954, Raper was appointed United States Attorney for Wyoming.

[6] After a decade in retirement, Raper died in Cheyenne, Wyoming on June 10, 1993.