The defense of Khe Sanh commanded international attention and was considered the climactic phase of the Tet Offensive. As these two elite enemy divisions, with history at Dien Bien Phu and the Ia Drang Valley, depleted, President Johnson ordered an air and naval bombing halt to most of North Vietnam as a gesture of peace. B-52s alone dropped more than 75,000 tons of bombs on North Vietnamese soldiers from the 304th and 325th Divisions encroaching the combat base in trenches. All three brigades from the First Cav participated in this vast airmobile operation, along with a Marine armor thrust.
Army's First Air Cavalry Division launched Operation Pegasus to break the siege of the Marine combat base-the second largest battle of the war. commanders hoped that the North Vietnamese Army would attempt to repeat their famous victory at the Battle of Dien Bien Phu, which would permit the U.S. Fighting began there in late April 1967 with the hill fights, which later expanded into the 1968 Battle of Khe Sanh. The airstrip was built in September 1962. Khe Sanh Combat Base was a United States Marine Corps outpost in South Vietnam ( MGRS 48QXD850418) used during the Vietnam War.