Originally published by the United States Marine Corps History Division in 2009.

In the 77 days from 20 January to 18 March of 1968, two divisions of the North Vietnamese Army (NVA) surrounded a regiment of U.S. Marines on a mountain plateau in the northwest corner of South Vietnam known as Khe sanh. The episode was no accident; it was in fact a carefully orchestrated meeting in which both sides got what they wanted. The north Vietnamese succeeded in surrounding the Marines in a situation in many ways similar to Dien Bien Phu, and may have been seeking similar tactical, operational, and strategic results. General William C. Westmoreland, the commander of the joint U.S. Military Assistance Command Vietnam (COMUSMACV), meanwhile, sought to lure the NVA into the unpopulated terrain around the 26th Marines in order to wage a battle of annihilation with air power. In this respect Khe Sanh has been lauded as a great victory of air power, a military instrument of dubious suitability to much of the Vietnam conflict. The facts support the assessment that air power was the decisive element at Khe Sanh, delivering more than 96 percent of the ordnance used against the NVA. This work focuses mainly on fixed-wing close air support, or the support provided by jet and propeller-driven conventional aircraft, to the general exclusion of rotary-wing aircraft, also known as helicopters. There are several reasons for this, none of which are meant to belittle the contributions or heroism of the Marine, Army, and Air Force helicopter pilots who fought in the hills around Khe Sanh. First, until the arrival of the AH-1G Cobra in April 1969, there was no helicopter designed for dedicated close air support of Marines in Vietnam. The primary gunship during the battle of Khe Sanh was the UH-1E outfitted with machine guns and rocket launchers for the escort of unarmed helicopters. These helicopters were sometimes used for the direct support of ground troops with suppressive fires and were frequently used as forward air controllers, spotting and marking targets for fixed-wing aircraft with heavier ordnance. These roles are appropriately discussed alongside the contributions of the fixed-wing aircraft, but as a general rule, analysis remains focused on the heavier attack aircraft.

The U.S. Marines history division has undertaken the publication of various studies, theses, compilations, bibliographies, monographs, and memoirs, as well as proceedings at selected workshops, seminars, symposia, and similar colloquia, which it considers to be of significant value for audiences interested in Marine Corps history. These "occasional papers," which are chosen for their intrinsic worth, must reflect structured research, present a contribution to historical knowledge not readily available in published sources, and reflect original content on the part of the author, compiler, or editor. It is the intent of the division that these occasional papers be distributed to selected institutions, such as service schools, official department of defense historical agencies, and directly concerned Marine Corps organizations, so the information contained therein will be available for study and exploitation. This manuscript was developed from a master's thesis written by then-Major Shawn P. Callahan while an Advanced degree program student at George Washington University. The research was financially supported by the naval historical Center's rear Admiral Samuel Eliot Morison naval history supplemental scholarship program and the Marine Corps heritage foundation's lieutenant Colonel Lily H. Gridle Memorial Master's thesis fellowship program. As an occasional paper, this work is presented with limited stylistic correction and essentially stands as the author's revised thesis.