He graduated from the United States Military Academy at West Point in 1925 and was commissioned as a second lieutenant of Cavalry.

[7] Harrold led his command during combat in Europe, including a key role in repelling the Germans during the Battle of the Bulge.

[13][14] Harrold served as Director of Civil Affairs for the United States Army European Command from 1947 to 1949.

[15][16] From 1949 to 1951, Harrold served as commander of the United States Army Armor School and Fort Knox.

He served from July 1951 to March 1952, receiving promotion to major general and leading the division during the Korean War.

[21][22] Harrold commanded the division during its stationing at Hokkaido, the northernmost island in Japan, where it carried out combat training, electronic surveillance and defense of Japan from potential attacks by the Soviet Union or China.