While participating in Operation Kingfisher, Barker's platoon was attacked by North Vietnamese forces in the western part of the Leatherneck Square.

On the morning of September 21 during Operation Kingfisher southeast of Con Thien near Phu Oc, the Battalion was ambushed by the 90th regiment of the 324B Division.

The Medal of Honor was presented to Barker's family by Vice President Spiro Agnew in ceremonies held on October 31, 1969.

The President of the United States in the name of the Congress takes pride in presenting the MEDAL OF HONOR posthumously to for service as set forth in the following CITATION: For conspicuous gallantry and intrepidity at the risk of his life above and beyond the call of duty while serving as a machine gunner with Company F, Second Battalion, Fourth Marines, Third Marine Division, in the Republic of Vietnam on 21 September 1967.

The squad immediately deployed to a combat formation and advanced to a strongly fortified enemy position, when it was again struck by small arms and automatic weapons fire, sustaining numerous casualties.

Unhesitatingly and with complete disregard for his own personal safety, Corporal Barker threw himself upon the deadly grenade, absorbing with his own body the full and tremendous force of the explosion.