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[inescap]able. There was an astonishing improvement in the combat effectiveness of the 9th Infantry Division when it was supported by airmobile and air cavalry assets. The last paragraph of the analysis bears repeating:
It is possible that not all divisions in Vietnam would generate statistical results similar to those of the 9th Division. The inundated flatlands of the Mekong Delta have a double impact on the spread of effectiveness between foot and airmobile operations. Marshy swamps and flooded rice paddies severely penalize ground troops. Units frequently are able to move no more than 500 meters per hour or less. On the other hand, the broad stretches of virtually flat Delta country provide an ideal environment for the unrestricted employment of Army aviation. Presumably such would not be the case in other areas of Vietnam. Statistics for other divisions might be expected to show improvements in combat effectiveness with air assets on the order of two or three to one, depending upon the circumstances. From the standpoint of II Field Force Vietnam, until analyses are made for the other divisions, it would appear worthwhile to allocate an additional assault helicopter company and an air cavalry troop to the 9th Infantry Division.
The A Shau Valley
On 10 April 1968 at landing zone STUD, General Rosson, the commander of Provisional Corps Vietnam, told me to plan immediate movement of the 1st Cavalry into the A Shau Valley. Though tentative plans had been made for operations against this enemy redoubt sometime before, I had no warning that the 1st Cavalry Division would be committed so quickly on the heels of our operations at Khe Sanh. The following day, we began extracting troops from Operation PEGASUS back into our base areas at Quang Tri City and Camp Evans.
The A Shau Valley lies between two high mountain ranges on the western edge of the Republic of Vietnam. On both sides of the valley the mountains climb to over 1,000 meters with the angle of slope varying from 20 to 45 degrees. The Laotian border is less than ten kilometers away. Three abandoned airfields were spread along the valley floor which runs northwest to southeast. The North Vietnamese forces had been in control of the valley since March 1966 when they overran the Special Forces camp in the southern end. Since that time they had built a major base for the infiltration of personnel and supplies from North Vietnam through Laos along Route 547 into Thua Thien Province and the northern I Corps Tactical Zone. (Map 7)
Final preparations for Operation DELAWARE-LAM SON 216 were conducted during the last days of Operation PEGASUS. The 1st