Losing Vietnam (4 page)

Table 3.
NVA/VC Order of Battle Strengths, Units in South Vietnam (in thousands)

Source
: Working papers, Headquarters USSAG, Nakhon Phanom, Thailand.

Integral unit moves out of South Vietnam did not include moves by enemy units into Laos and Cambodia to escape allied security operations, since these were considered temporary. The average annual North Vietnamese Army infiltration rate, about 120,000 men, was in accordance with that nation's demographic capabilities. North Vietnam, with a population of about 23.5 million, had about 4.3 million males between the ages of fifteen and forty-nine years. The number of males reaching draft age yearly was about 200,000 to 250,000, and of those it was estimated that 130,000 to 140,000 were physically fit.
Table 3
indicates the probable order of battle strengths for the NVA
and VC components at the beginning of 1967, 1973, and 1975. In 1967 the order of battle was made up primarily of Viet Cong forces; however, after the 1972 campaign the preponderance of enemy was North Vietnamese, and by 1975 it was their war. Even in 1967, the enemy ground combat units were almost evenly distributed between the NVA and VC. None of this data includes the Viet Cong political infrastructure, which was always at least 30,000 people.

When assessing comparable strengths, one must also consider those enemy units along major supply routes and storage areas in Laos and Cambodia, as well as the combat and training divisions stationed in North Vietnam. The North Vietnamese strategic reserve was to play a vital role in 1975. Consequently, an estimate of enemy strengths in late 1974 and early 1975 was 340,000 for South Vietnam, 50,000 for Laos, 30,000 for Cambodia, and 70,000 for North Vietnam, for a total of 490,000 troops.
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The enemy used infiltration, the primary operational key to any military estimate, to modernize and rebuild units, replace people, stock supplies, and position units for the end-of-the-war offensive. They learned major lessons from their 1972 Easter Offensive: first, secure logistical bases were necessary to resupply forces until they seized their objectives; and second, to be successful, attacking troops had to employ large-scale combined arms tactics. Also, the enemy learned that the awesome firepower of the U.S. Air Force could disrupt logistical bases, lines of communication, and attacking troops.

The signing of the peace accords eliminated the potential of U.S. air strikes. Afterward the North placed its highest priority on improving and expanding lines of communication, road networks, airfields, and pipelines, to better enable them to push supplies and equipment to the South. In the past, the North Vietnamese had had no problems receiving war matériel from supporting countries, but with the severe air interdiction they had difficulty transporting supplies to the front. The RVNAF, however, had difficulty ultimately in receiving its required war matériel from the United States, but with interior lines it generally had little difficulty in getting what it had into the hands of the troops.

Photo 1. Traffic on the Ho Chi Minh Trail, 21 December 1973. (Source: Headquarters USSAG, Nakhon Phanom, Thailand, produced by the 432nd Reconnaissance Technical Squadron, U.S. Air Force.)

By mid-1974 significant new numbers emerged.
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The 770-mile stretch of the Ho Chi Minh Trail running through Laos was broadened and improved, much of it even paved. Transport by A-frames was a thing of the past. USSAG's air reconnaissance often showed three trucks abreast traveling south with matériel. The enemy built innumerable roads leading from the jungle areas of the Ho Chi Minh Trail to the coastal plains. They also developed a second major infiltration corridor within South Vietnam; this ran parallel to the Ho Chi Minh Trail, extending from the demilitarized zone to the border area a hundred miles north of Saigon. This second trail, of about 600 miles, terminated in base areas in the northwestern sector of Tay Ninh Province.

The modern equipment being infiltrated required a steady supply of petroleum. The enemy extended its 30-centimeter pipeline through Laos and built a second internal pipeline; in October 1974, the combined length of both was 470 kilometers. During the twenty months since the cease-fire, the enemy had set up an important network of petroleum storage areas that consisted mainly of twenty-thousand-liter containers hidden underground in groups of four to six, linked to the pipeline system. These depots contained 13.5 million liters of petroleum; prior to the cease-fire this number was 1 million liters.

In an effort to modernize the North Vietnamese Army units, the enemy made maximum use of its vastly improved lines of communication to infiltrate men and equipment. Although five divisions and six infantry regiments had been withdrawn or deactivated, the North Vietnamese introduced a sapper division and an antiaircraft division as well as twenty antiaircraft, five sapper, three armored, and three artillery regiments. To commit a modern conventional army in open combat, the enemy was balancing its forces to include a combined arms orientation to offset South Vietnam's capabilities.

The troop levels are indicated in
figure 1
. Combat troops increased by 54,000 to 206,000, and combat support troops almost doubled, increasing to 108,500. This data varies somewhat from the order of battle data kept by the United States. The increases in combat support were necessary to man the improved logistical support complex fed by the improved lines of communication. The large increases in troop levels were disquieting, but the dramatic reduction of the reinforcing time for infiltration was almost as important. Prior to 1973, troop replacements headed for the delta had taken about four months, whereas in late 1974 the trip took less than two weeks. This ability to quickly relocate reserve divisions in North Vietnam to the battlefield would greatly influence events in March–April 1975. After the cease-fire, the North Vietnamese Army infiltrated more than 200,000 troops.

To modernize the combat capabilities of these troops, the enemy infiltrated numerous tanks, artillery, and antiaircraft equipment. Since most of the armored vehicles were destroyed in battle in 1972, it introduced 655 tanks and tracked vehicles. This included several new types of equipment, such as the T-34 bridge-laying tank.

A substantial number of guns upgraded the artillery capability,
bringing the total to 430 Russian-made 122 mm and 130 mm field guns. The Soviet 122 mm howitzers and the 122 mm and 130 mm guns outranged the U.S.-supplied 105 mm and 155 mm howitzers, which the ARVN primarily relied on. The ARVN did have five 175 mm artillery battalions with twelve guns each that had an effective range greater than the Soviet pieces.

Figure 1. Enemy Troop Levels. (Source: RVNAF briefing, “Logistics,” JGS, J-4, September 1974, Saigon, South Vietnam.)

However, the most disturbing aspect of the infiltration was the
introduction of twenty air defense regiments and their equipment. No longer required to protect their homeland against an air attack, the North Vietnamese moved ultra-modern and effective radar systems to South Vietnam. This was the unintended consequence of the unilateral U.S. bombing halt of North Vietnam, which in fact negated much of the VNAF's firepower.

These newly infiltrated antiaircraft and radar systems, which provided enemy air surveillance over almost all of South Vietnam, required the South Vietnamese Air Force to fly at altitudes of ten thousand feet, thereby greatly reducing its effectiveness in close air support. These sophisticated systems guarding the lines of communication and military base areas preempted the possibility of the VNAF effectively disrupting the enemy's logistical system, which the U.S. Air Force had done so effectively in earlier years, since the Vietnamese Air Force did not have the sophisticated electronic countermeasures equipment required.

The massive infiltration of equipment into South Vietnam required the North Vietnamese to reorganize their force structure. They reduced infantry divisions and regiments and increased artillery and sapper divisions and separate regiments and substantially increased air defense regiments. Six armored regiments infiltrated to exercise command over the 655 tanks known to be in South Vietnam. The enemy now had the organization and equipment to conduct combined arms offensives. It had fallen short in the past in command and control, which resulted in uncoordinated piecemeal attacks. To remedy that situation, it was reportedly forming four new corps headquarters that would enable control of multidivisional combined arms forces on a conventional warfare battlefield. The communists were also creating additional divisional structures from units already in South Vietnam. Sufficient heavy weapons and artillery were available to provide firepower support for these new divisions.
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At the end of 1974, North Vietnam had more troops, more equipment, and more supplies available in South Vietnam than ever before. The stage was set to launch a major dry-weather offensive when they decided to do so. In December, when the NVA was creating new units and infiltrating soldiers at an increased rate, Gen. Cao Van Vien noted that his joint staff was conducting a study to convert all possible rear
service personnel into infantry units in a desperate effort to obtain additional combat strength.

The lifeblood of the North's aggression against South Vietnam was the infiltration routes that brought equipment, supplies, and troops from North Vietnam to the South.
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The enemy could not successfully mount a major offensive without logistical staying power; consequently, it relied on the buildup of base areas located in relatively close proximity to its military objectives. The main infiltration routes ran through Laos and Cambodia and continued to do so, in violation of Article 20, after the signing of the January 1973 cease-fire agreement.

Notwithstanding the importance of the infiltration routes and base areas in Laos and Cambodia, the RVNAF conducted only two major cross-border operations. When Cambodian president Lon Nol closed the port of Sihanoukville (Kompong Som) in 1970, he effectively cut the NVA's supply route to South Vietnam's MR-4. This required the NVA to resupply base areas supporting MR-3 and -4 to infiltrate overland from North Vietnam. The RVNAF's May 1970 joint operation with U.S. forces against the enemy base areas located in Cambodian sanctuaries destroyed great quantities of war materials. Then in February 1971, in another joint endeavor, Lam Son 719, the RVNAF launched a major operation into southern Laos, this one designed to interdict the Ho Chi Minh Trail, now the major resupply route, and to occupy and destroy major enemy logistics bases. Both of these cross-border operations were strategically successful in buying time for the key Vietnamization program so essential since the United States was withdrawing its troops. However, from a tactical point of view Lam Son 719 left very much to be desired, since it did not destroy the enemy base areas and it exposed ARVN inadequacies. While the ARVN may have been seen to have failed, the enemy also showed major weaknesses. Since the cease-fire, ralliers indicated NVA troop morale declined, as it became increasingly clear that the war was not over or even almost over. There continued to be a very definite amount of debilitating friction between the southern and northern communists. In many ways, the loss of morale was not due to any new concrete problems—hardships, friction between northerners and southerners, and the stresses of
life under communist control had been present all along—but once the hope of the war's ending was dashed, existing problems suddenly were less bearable than before. Huynh Van Tan, commander of the 200C Sapper Battalion, said he rallied against the fear of being killed, discrimination against southerners, lack of discipline, and the fact that the dissension between northerners and southerners sometimes resulted in fighting and killing.
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