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.