Vietnam War Congressional Medal of Honor Recipient. He served as a Sergeant, United States Army, Company D, 5th Special Forces Group (Airborne). He was awarded his medal posthumously for service Near Thong Binh, Republic of Vietnam, on January 16-18, 1968. His citation reads-For conspicuous gallantry and intrepidity in action at the risk of his life and above and beyond the call of duty. Sgt. Yntema, U.S. Army, distinguished himself while assigned to Detachment A-431, Company D. As part of a larger force of civilian irregulars from Camp Cai Cai, he accompanied 2 platoons to a blocking position east of the village of Thong Binh, where they became heavily engaged in a small-arms fire fight with the Viet Cong. Assuming control of the force when the Vietnamese commander was seriously wounded, he advanced his troops to within 50 meters of the enemy bunkers. After a fierce 30 minute fire fight, the enemy forced Sgt. Yntema to withdraw his men to a trench in order to afford them protection and still perform their assigned blocking mission. Under cover of machinegun fire, approximately 1 company of Viet Cong maneuvered into a position which pinned down the friendly platoons from 3 sides. A dwindling ammunition supply, coupled with a Viet Cong mortar barrage which inflicted heavy losses on the exposed friendly troops, caused many of the irregulars to withdraw. Seriously wounded and ordered to withdraw himself, Sgt. Yntema refused to leave his fallen comrades. Under withering small arms and machinegun fire, he carried the wounded Vietnamese commander and a mortally wounded American Special Forces advisor to a small gully 50 meters away in order to shield them from the enemy fire. Sgt. Yntema then continued to repulse the attacking Viet Cong attempting to overrun his position until, out of ammunition and surrounded, he was offered the opportunity to surrender. Refusing, Sgt. Yntema stood his ground, using his rifle as a club to fight the approximately 15 Viet Cong attempting his capture. His resistance was so fierce that the Viet Cong were forced to shoot in order to overcome him. Sgt. Yntema's personal bravery in the face of insurmountable odds and supreme self-sacrifice were in keeping with the highest traditions of the military service and reflect the utmost credit upon himself, the 1st Special Forces, and the U.S. Army.
SGT Yntema is on panel 34E, row 73 of the Vietnam Memorial Wall in Washington D.C.