The Easter Offensive in southern Cambodia and the Mekong Delta was part of the People’s Army of Vietnam (PAVN)’s Easter Offensive of 1972 and saw PAVN and Viet Cong (VC) engage the Army of the Republic of Vietnam (ARVN) and Khmer National Armed Forces (FANK) supported by the United States along the southern Cambodian border with South Vietnam and in the Mekong Delta of South Vietnam. The offensive failed to seriously disrupt the vital South Vietnamese supply routes in the Delta or the pacification efforts there.
Background The Mekong Delta was the heartland of agricultural South Vietnam, it encompassed the fertile alluvial plains formed by the Mekong River and its main tributary, the Bassac River. With its sixteen provinces, the Delta contained about two-thirds of the nation's population and yielded the same proportion in rice production. The terrain of IV Corps differed radically from other regions. Flat and mostly uncovered, it consisted of mangrove swamps and ricefields crisscrossed by an interlocking system of canals, natural and artificial. Except for some isolated mountains to the west near the Cambodian border, few areas in the Delta had an elevation of more than above sea level. During the monsoon season, most of the swampy land north of Route QL-4, generally called the Plain of Reeds, was inundated, especially when alluvial waters raised the level of the Mekong River from July to October. Other undeveloped swampy areas along the coast had turned into havens that sheltered VC main force units just as the scattered bases inland offered good refuge for local guerrillas.
ARVN forces under the control of IV Corps consisted of three infantry divisions, two mobile and six Border Ranger groups. In addition, the Regional and Popular Forces of MR-4 totaled about 200,000, by far the most numerous among the four military regions. The ARVN 7th Division was headquartered at Đồng Tâm Base Camp in Định Tường Province; the 9th Division was located in Sa Đéc and the 21st Division usually operated in the Cà Mau Peninsula from its headquarters at Bạc Liêu. Despite the substantial combat support and significant advisory effort, both military and civilian, provided by the United States, primary responsibility for the combat effort in MR-4 had always been Vietnamese, even during the period when U.S. units operated in the Mekong Delta.
Central Office for South Vietnam (COSVN) emphasized the strategic importance of the Mekong Delta and conceived it as the principal battlefield where the outcome of the war in South Vietnam would be decided and in early 1970 it infiltrated the PAVN 1st Division Headquarters and its three regiments, the 88th, 95A and 101D into MR-4. This effort succeeded despite heavy losses. IV Corps forces were thrown off-balance and the pacification effort declined as a result of extensive PAVN attacks and shellings. Not until after the PAVN sanctuaries beyond the border had been destroyed during the Cambodian Campaign and their capability to resupply from the sea eliminated were these 1st Division forces compelled to break down into small elements and withdraw. Part of these elements fell back into mini-bases within MR-4; others retreated toward Cambodia.
IV Corps was therefore able to regain the initiative during 1971. Its efforts during the year consisted of continuing operations on Cambodian soil to assist the weaker Khmer National Armed Forces (FANK) and interdicting enemy supply routes into the Mekong Delta. Concurrently, it also emphasized the elimination of the PAVN/VC bases in the Delta. ARVN forces succeeded in penetrating and destroying most of these bases. In addition, they also established a new system of outposts to maintain South Vietnamese government control over what had been the PAVN/VC’s long-established base areas. The most significant achievements during this period were the neutralization of the extremely heavy enemy fortifications in the Bảy Núi area by the ARVN 9th Division, the continued destruction of PAVN/VC installations in the U Minh Forest by the 21st Division, the coordinated activities of the 7th Division and territorial forces in Base Area 470 on the boundary of Định Tường and Kien Phong Provinces, and finally, the successful pacification campaign in Kien Hoa Province, the cradle of VC insurgency.
As a result of these achievements by early 1972 about 95% of the Delta population lived in secure villages and hamlets. Rice production had increased substantially and education was available to every child of school age. Key South Vietnamese government programs such as Land-to-the-Tiller and Hamlet Self-Development were gaining momentum and in March 1972 the government initiated the four-year Community Defense and Local Development Plan.
Prior to the Easter Offensive PAVN/VC activities in the Delta were at a low level, consisting mostly of small-unit attacks, harassment of outposts and scattered road interdiction. The PAVN/VC seemed to be concentrating their effort on building up supplies in his base areas, particularly in the U Minh Forest and in Định Tường Province, preparing for future attacks. At that time, PAVN/VC forces in the Mekong Delta consisted primarily of six local force regiments, all implanted in their safe havens. The 18B and 95A Regiments were in the U Minh area; the D1 and D2 Regiments were reported southwest of Chương Thiện Province; the D3 Regiment was scattered along the common boundary of Vĩnh Long and Vĩnh Bình Provinces; and the Dong Thap 1 Regiment was located in an area south of Route QL-4 in Định Tường Province. Probable reinforcements from beyond the Cambodian border included the PAVN 1st Division which might be introduced into Châu Đốc and Kiên Giang Provinces and the Z15 Regiment north of Kiến Tường Province.
During this time, the defense of the border for MR-4 was assigned to the 44th Special Tactical Zone (STZ) whose Border Ranger and armor forces were deployed as a screen along the Cambodian border from the Parrot's Beak area to the Gulf of Thailand. In addition to its territorial defense responsibility inside MR-4, the 44th STZ also operationally controlled two major bases in Cambodia, Neak Loeung, at Highway 1 (Cambodia) ferry crossing of the Mekong River and Kompong Trach, some 20 km north of Hà Tiên. Both bases were secured by ARVN ranger forces. The 9th Division was then conducting operations in the upper U Minh area and in Chương Thiện Province while the 21st Division operated in the lower U Minh area and in the southern portion of the Cà Mau peninsula. Meanwhile, the 7th Division was responsible for the two contested areas of MR-4, Định Tường and Kien Hoa Provinces, and other provinces sandwiched between the Mekong and Bassac Rivers.
In mid-March, an ARVN intelligence report indicated that the entire PAVN 1st Division was moving southward in Kampot Province, Cambodia, to an area deeper south than where it had been in late 1970. Two other PAVN regiments, 18B and 95A, were also reported leaving the U Minh area and moving eastward in the direction of Chương Thiện Province. These movements undoubtedly presaged major actions in the Mekong Delta during the 1972 dry season.
Offensive Battle of Kompong Trach Kompong Trach was a small Cambodian town located near a road intersection in a lightly forested area north of Hà Tiên, about 15 kilometers north of the border. IV Corps maintained an operational base there which controlled one of the PAVN/VC's major supply routes from Cambodia into the Mekong Delta.
The battle for Kompong Trach started on 22 March with an engagement between elements of the 42nd Ranger Group and the PAVN 101D Regiment and did not abate until the end of April. Apparently, it had not been the PAVN's choice to fight a major battle in this area at this time. The initial engagement, however, developed into a significant battle as reinforcements kept pouring in from both sides. On the ARVN side, a large force was committed which eventually consisted of four armored cavalry squadrons, including the 7th Division's organic squadron, deployed across the entire width of MR-4 from its easternmost corner over one hundred kilometers away, six Ranger battalions, artillery units and supporting engineer elements. The PAVN initially committed only the 101D Regiment and supporting elements of the 1st Division. Eventually, however, they were forced to throw in two additional regiments in rapid succession, the 52nd (aka E46) and E44, which were then on their way into MR-4.
In spite of heavy losses incurred by both sides and the fact that eventually the ARVN base at Kompong Trach had to be evacuated, the battle resulted in a major defeat for the PAVN. The 1st Division, which was the only division size unit committed to the Mekong Delta at that time, had been forced to exhaust its combat potential on Cambodian soil whereas it was apparently needed to conduct major actions inside MR-4 in concert with the Easter Offensive and their mission to destroy the pacification progress in IV Corps caused only minor disruption. Heavy losses were inflicted on the 1st Division by ARVN armor firepower and the devastating U.S. Air Force (USAF) and Republic of Vietnam Air Force (VNAF) airstrikes during massed infantry assaults.
Hậu Giang While the battle at Kompong Trach was raging, the PAVN/VC initiated offensive activities in the Mekong Delta with a series of attacks on 7 April. Most of these attacks occurred in Chương Thiện Province. They were conducted by four local main force units, the 18B, 95A, D1 and D2 Regiments, which almost in unison endeavored to destroy all ARVN bases and outposts along the PAVN/VC communication routes. These routes originated in the large U Minh base area, ran through the provinces of Chương Thiện and Phong Dinh, then connected the Hậu Giang Province area (west of the Bassac River) with Tiền Giang Province (east of the Mekong River).
Elsewhere in the Delta, PAVN/VC main force and local units also surfaced to put pressure on RF/PF forces in an attempt to disrupt the South Vietnamese pacification program. Despite the fact that these attacks were spread over a large geographical area, the PAVN/VC offensive affected only remote outposts and territorial forces, almost to the exclusion of ARVN main force units. To help maintain tactical balance for MR-4, U.S. tactical air and B-52 strikes, which had not been used in the Delta since the beginning of 1972, resumed in support of ARVN forces at Kompong Trach and in other areas under contest throughout MR-4. This air support had a significant impact on the outcome of the PAVN/VC offensive. Without it, it is doubtful that the ARVN ground forces would have been able to defeat so decisively the large PAVN/VC forces engaged in these battle areas.
On 7 April, the day PAVN/VC attacks began in MR-4, the 21st Division was ordered to prepare for movement to MR-3. By 10 April the first elements of this division were already deployed along Route QL-13 north of Lai Khê. Then on 12 May, another MR-4 unit, the 15th Regiment, 9th Division, was deployed to MR-3 in the effort to relieve PAVN pressure on An Lộc. These redeployments resulted in voids which would affect the defense posture of MR-4. Consequently, IV Corps had to readjust the tactical areas of responsibility over the entire border area with its mobile and Border Ranger units, to include a Ranger group just released from its reinforcement mission in MR-1. The 9th Division took over responsibility for all the provinces in the Hậu Giang/Bassac area while the 7th Division was given responsibility for the Tiền Giang/Mekong area with the majority of its effort concentrated north of Route QL-4.