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in Vietnam, since all other details are covered in the specific history of the 1st Cavalry Division.

The 1st Cavalry Division had been operating in the Binh Dinh Province through four successive campaigns since early 1966—Operations THAYER I, IRVING, THAYER II, and the then current campaign, PERSHING. The 1st Cavalry had put intense pressure on the North Vietnamese Army 3d Division and its three main force regiments throughout these campaigns. They had suffered severe logistical and personnel losses. Relentlessly pursued in every portion of the province, the remaining North Vietnamese Army units were forced to find an area in which they could regain strength and reorganize their ranks. Consequently, the 2d Viet Cong Regiment as early as mid-October 1966 had retreated north into Quang Ngai Province to avoid the 1st Cavalry. The 22d North Vietnamese Army Regiment also withdrew into Quang Ngai during the month of March. These frequent enemy retreats to the north, to rest and regroup, contributed to the necessity for the 1st Cavalry's participation in Operation LEJEUNE which began on 7 April. The principal reason behind this operation was an urgent Marine requirement to free some of their troops in Quang Ngai for movement further north.

The boundary between the provinces of Quang Ngai to the north and Binh Dinh to the south established the demarcation line between the I Corps and II Corps Tactical Zones. This same boundary line divided the U.S. military effort, with the III Marine Amphibious Force having the responsibility in the I Corps area.

Throughout its previous nineteen months of operations in Vietnam, the 1st Cavalry had never operated outside of the II Corps area and, as a matter of fact, no U.S. Army combat unit had operated in the I Corps Tactical Zone. The enemy (with some reason) had assumed that they would be secure by moving into the "safe" area of Quang Ngai Province and thus elude the seemingly endless pursuit by the 1st Cavalry Division. This proved to be a mistaken assumption for on the 7th of April an Air Cavalry battalion task force moved into Duc Pho in the southernmost district of Quang Ngai.

The Duc Pho area had been effectively controlled by the communists for more than ten years. Over the years the Viet Cong and its political arm, the National Liberation Front, had increased their power by political indoctrination, torture, and terrorism until