along Route 547A. The 1st Air Cavalry Division was to conduct concurrent operations, partially as a deception, to the north and east of the valley.

South of the 101st Airborne Division's area of operations in Thua Thien Province lay that of Marine Task Force X-Ray, under the command of Brigadier General George D. Webster. On l June, Phase III of Operation Houston began under the control of the 5th Marines. National Route l, from Phu Bai south to the Hai Van Pass, was successfully kept open as elements of Colonel Paul G. Graham's regiment provided security for key bridges and installations and conducted patrols and ambushes on avenues of approach to the vital highway. In addition, the regiment conducted extensive rice denial operations in the Phu Thu and Vinh Loc Districts, east and southeast of Phu Bai, in conjunction with South Vietnamese Regional and Popular Forces. During the month, the Marines captured more than 31,000 pounds of rice and returned them to government control, and relocated more than 44 tons to secure storage areas. The regiment also conducted a number of short operations in the jungle canopy south of the Phu Bai vital area, in the Phu Loc and Hai Van Pass areas of the operation, to locate and destroy enemy forces, supply caches, and base areas.

THE DEFINING YEAR

During Phase IV of Operation Houston, which began on l July, Task Force X-Ray assumed operational control of BLT 2/7, which on 9 July assaulted into the Vinh Loc District by helicopter and amphibian tractors, and continued the task force's vigorous rice denial campaign. A week later, the battalion landing team joined the 5th Marines and was helilifted to the Thon Mu Kham Valley, southwest of Phu Bai, where fire support bases were constructed and search operations begun. With the departure of the battalion landing team and the 5th Marines, Colonel Bruce F. Mey-ers' 26th Marines, assumed tactical responsibility for the Task Force X-Ray area of operations and began Phase V of Operation Houston on 25 July.*

Throughout the summer months, Marine, U.S. Army, and ARVN troops continued the relentless and successful pursuit and destruction of enemy forces in northern I Corps. From Thon Mu Kham Valley in the south to the Demilitarized Zone in the north, allied forces aggressively and repeatedly forced the North Vietnamese troops and their Viet Cong allies to withdraw deeper into their border sanctuaries, thereby delaying any enemy attempt at initiating a major offensive in the northern two provinces of South Vietnam.

*For the beginning of Operation Houston see Chapter 13.