On March 24, 1967, the 1st Battalion, 9th Marines began Operation Prairie III; that same day, in the Gio Linh District, Quang Tri Province, Sergeant Singleton's Company A came under intense enemy fire at the village of Phu An.

Sergeant Singleton's company was conducting combat operations in Gio Linh District, Quang Tri Province, Republic of Vietnam, when the lead platoon received intense small arms, automatic weapons, rocket, and mortar fire from a well entrenched enemy force.

As the company fought its way forward, the extremely heavy enemy fire caused numerous friendly casualties.

Sensing the need for early treatment of the wounded, Sergeant Singleton quickly moved from his relatively safe position in the rear of the foremost point of the advance and made numerous trips through the enemy killing zone to move the injured men out of the danger area.

Sergeant Singleton's bold actions completely disorganized the enemy defense and saved the lives of many of his comrades.

His daring initiative, selfless devotion to duty and indomitable fighting spirit reflected great credit upon himself and the Marine Corps, and his performance upheld the highest traditions of the United States Naval Service.