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.

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.

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.

[1]: 141 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.

[1]: 142 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.

[1]: 144 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.

Heavy losses were inflicted on the 1st Division by ARVN armor and the devastating U.S. and Republic of Vietnam Air Force (RVNAF) airstrikes during massed infantry assaults.

They were conducted by four local main force units, the 18B, 95B, D1 and D2 Regiments, which almost in unison endeavored to destroy all ARVN bases and outposts along the PAVN/VC communication routes.

[1]: 148 In the meantime, indications were being obtained by ARVN-U.S. intelligence of a strong enemy buildup in the Parrot's Beak and Elephant's Foot (10°52′N 105°54′E / 10.87°N 105.9°E / 10.87; 105.9) areas near the border in northern Kiến Tường Province.

Then on 10 June, prisoner sources disclosed that the PAVN 5th Division, which had failed in its earlier effort to take An Lộc in MR-3, was being redeployed to the Elephant's Foot area on Cambodian territory.

[1]: 149 To the IV Corps commander, Major General Nguyễn Vĩnh Nghi, who had participated in MR-3 operations during the initial stage of the siege of An Lộc, it became evident that after being defeated there, the hungry 5th Division was trying to seek refuge in the food-rich Mekong Delta.

Actually, a new phase of the PAVN offensive was about to begin that would involve IV Corps forces in major battles not only in the Tiền Giang area but also in Cambodia.

These weapons curtailed the activities of our helicopters and observation planes and inflicted extensive damage on RVNAF aircraft but intercepted by the 7th Division forces while on the move, PAVN units were surprised and suffered heavy losses.

[1]: 150 In the meantime, and in conjunction with PAVN efforts to infiltrate the Tiền Giang area, other units, probably elements of the 9th Division, began moving toward Kompong Trabek which they took in mid-June.

With the support of local Khmer Rouge units, these PAVN forces were endeavoring to tighten control over Route QL-1 from the Parrot's Beak area to Neak Loeung on the Mekong River.

After 22 days of fighting, ARVN forces succeeded in recapturing Kompong Trabek and clearing Route QL-1 westward after a link-up with Neak Loeung.

To defeat the PAVN/VC effort against Route QL-4 in Định Tường, B-52 strikes were concentrated on PAVN/VC bases in the Delta whenever fighting became intense and profitable targets were detected.

[1]: 151 In mid-August, as the situation in Bình Long Province became stabilized, the 21st Division was returned to MR-4 and reassigned the responsibility for the southern Hậu Giang area, its former territory.

The 44th STZ meanwhile was assigned the responsibility for the area west of the Mekong River and south of the Cambodian border, to include the eastern part of Kiến Phong Province.

This enabled IV Corps to rebuild a system of outposts along the Tháp Mười Canal and reestablish South Vietnamese government control over this area which had been subverted by the PAVN/VC since the beginning of the Easter Offensive.

[1]: 152 In late August and early September, IV Corps shifted its effort toward the Bảy Núi area in Châu Đốc Province where intelligence reports strongly indicated reinfiltration by elements of the PAVN 1st Division In a quick move, IV Corps brought its forces westward into Châu Đốc and across the Cambodian border into an area west of Nui 0.

[1]: 152–3 The official PAVN history claims that the PAVN/VC "eliminated more than 30,000 enemy troops from the battlefield, annihilated ten enemy battalions, attacked and crippledfive regiments of the 7th and 9th Divisions, annihilated or forced 500 outposts to surrender, liberated 350,000 people and gained control of over 72 villages in Mỹ Tho Province and in parts of Bến Tre, Kiến Phong and Kiến Tường Provinces.

South of the Bassac River, the PAVN 18B, 95A, D1 and D2 Regiments simultaneously moved eastward, establishing blocking positions along lines of communication and among populous areas.

During a battle in the Hồng Ngự District where the Mekong River crossed the border, elements of the Division, in coordination with RF/PF forces, annihilated a battalion of the PAVN 207th Regiment, taking 73 prisoners during eight days of engagement.

[1]: 154 Meanwhile, farther west of the Bassac River, Ranger forces of the 44th STZ conducted successful operations in Hà Tiên Province and the Bảy Núi area.

IV Corps took advantage of this respite to readjust command and control, expanding the 7th Division's TAOR to include both Dinh Tuong and Gò Công Provinces as the first step.

It was obvious then that the October pattern was repeating itself and the PAVN/VC were apparently more concerned with their omni-presence as a psychological and political ploy to influence the local population and stimulate the morale of their own troops than trying to obtain military gains.

Although not as dramatic as the combat exploits achieved in An Lộc, Kontum or Quảng Trị, IV Corps won the battles in the Mekong Delta while sharing nearly half of its forces with MR-3 and MR-1.