Completing his recruit training at Marine Corps Recruit Depot San Diego, California, he was temporarily in the 1st Guard Company at that base, prior to his transfer to Headquarters and Service Company, 2nd Battalion, Camp Elliott, San Diego, California, in September 1942.

Sgt Harrell earned the Medal of Honor during the Iwo Jima campaign for continuing to halt a Japanese advance toward his Command Post although suffering from the loss of both hands and several saber cuts on his legs.

On March 3, 1945, Sgt Harrell and another man dug in for the night in a long narrow two-man foxhole on Iwo Jima, on a little ridge 20 yards forward of the depression where the company command post was established.

Thinking he was dying due to the severity of his wounds and saber cuts suffered in the last repulse, Sgt Harrell ordered his companion to retire to safety.

He was presented the nation's highest military decoration by President Harry S. Truman at the White House on Friday, October 5, 1945.

Sometime after midnight on August 9, in his own residence, Harrell shot and killed his friends, Edward and Geraldine Zumwalt, and then turned the gun on himself.