The service divisions corresponded to their predecessor elements in MACV, except for the advisory role, their basic missions being to support the self-sufficiency of the South Vietnamese military.
When DAO Saigon became operational in late January 1973, no fewer than 383 separate contracts were on the books with a total value of US$255 million.
In January 1973, over 23,000 people were employed by contractors in South Vietnam, of whom over 5,000) were Americans, 16,000 were Vietnamese, and the remainder were third-country nationals.
Although most contract employees were located in the Saigon region, sizable groups were at the air bases at Da Nang, Pleiku, Phù Cát, Phan Rang and at Binh Thuy.
[3]: 514–6 In late December 1973, fearing that ARVN forces in I Corps could be trapped if the PAVN interdicted Route 1 north of the Hải Vân Pass and face "Dunkirk without ships", Murray requested an additional six Landing Ship, Tank (LST)s to supplement the nine already in the Vietnamese Navy and for the dredging of the channel from Thuận An to Tân Mỹ Base to allow LST access.
Pentagon lawyers refused the request for additional LSTs as a possible breach of the restrictions agreed in the Paris Peace Accords.
[5]: 94 In January 1974 Murray met General Cao Văn Viên, chairman of the JGS to emphasise the need to conserve ammunition.
Following this meeting Viên met with his head of logistics General Dong Van Khuyen and they agreed to cut ammunition and fuel supplies for all units.
On the other hand, the PAVN not only possessed considerable flexibility in choosing objectives and selecting forces to employ, but it also had six full-strength infantry divisions, adequately supported by artillery, tanks and supplies, to throw into the battle at the decisive moment.
In the interim, DAO Saigon requisitioned supplies and equipment for the South Vietnamese military under continuing Congressional resolution authority, based on the program of assistance developed jointly with South Vietnam's Defense Ministry and JGS in early 1973 and in anticipation of adequate funds in the Defense Appropriation Act for FY 1974.
[5]: 124–5 On 11 June 1974, the United States Senate passed the FY 75 Military Procurement Bill with a US$900 million limit on Vietnam MASF.
In a Senate-House conference the limit was raised to US $1 billion, and a bill including that amount was signed by President Gerald Ford on 5 August, but it soon became apparent that the appropriation for South Vietnam would be much less.
[1]: 87 The DAO calculated that at this funding level by 30 June 1975 the South Vietnamese military would have only a 30 day supply of ammunition and almost no fuel.
"[5]: 63 In August 1974 the DAO recommended a substantial reduction in RVNAF training in the United States in order to save costs.
[1]: 87 Hunt continued the conferences and working sessions between DAO and JGS staffs to revise the MASF program within the US$700 million appropriation.
[6]: 433 General Smith later wrote that "crippling limitations were imposed on... firepower and mobility... All of this had a debilitating effect on morale and gave strong encouragement to the enemy.
The DAO and the Embassy each reported in their own channels events which presaged the approaching campaign and both were occupied with furnishing information to Washington to support the supplemental appropriation for Vietnam military assistance requested by the Ford administration.
To see first-hand the situation which the White House said justified at least the US$300 million requested several members of Congress and their staff aides journeyed to South Vietnam.
[1]: 144 DAO presented these congressional visitors with its estimate of the numerical strength changes that had taken place in PAVN forces in South Vietnam since the ceasefire.
This explained frequently unperceived influences on the relative power, flexibility and tactical potential of the opposing armed forces.
The South Vietnamese, even when they were able to discover the enemy's intent in advance, were often unable to move sufficient reserves to the battle area in time to forestall defeat in detail.
[5]: 223 On 26 March Smith diverted tugs and barges that had been used in ferrying supplies up the Mekong to Phnom Penh to assist in the evacuation of Danang.
[5]: 324 An Alternate DAO Programs Activity Office was established at Nakhon Phanom in April to administer military assistance and on 18 April the chief of the military assistance division was directed to proceed to Nakhon Phanom, it was expected that up to 100 staff would follow, however this movement was overcome by events.
[7]: 38 On 4 April 1975 35 DAO employees acting as escorts during Operation Babylift were killed when their USAF C-5 transport plane crashed near Tan Son Nhut.
[8]: 196 At 03:30 on 29 April 1975 a PAVN rocket hit Guardpost 1 at the DAO Compound, instantly killing Marine Security Guard Corporals Charles McMahon and Darwin Judge, they would be the last American ground casualties in Vietnam.
During their approach to the compound, they experienced a firsthand view of the PAVN's firepower as they shelled nearby Tan Son Nhut Airport with ground, rocket and artillery fire.
They quickly established an austere command post in preparation for the arrival of the Marine CH-53s and the ground security force.
[8]: 186 "Alpha" command group, two rifle companies and the 81mm mortar platoon were deployed around the DAO Headquarters building (the Alamo) and its adjacent landing zones.
[8]: 195 At 19:30 Carey directed that the remaining elements guarding the Annex be withdrawn to DAO Headquarters (the Alamo) where the last of the evacuees would await their flight.
[8]: 197 At 00:30 on 30 April, Thermite grenades, having been previously placed in selected buildings, ignited as two CH-53s left the DAO parking lot carrying the last elements of BLT 2/4.