The An Lộc defenders were later reinforced by the elite 81st Ranger Group and the 1st Airborne Brigade, brought in by air after failing to pass the PAVN block at Tàu Ô.

During North Vietnam's Easter Offensive (known in Vietnam as the Nguyen Hue Offensive) of 1972, An Lộc was at the centre of the PAVN strategy, its location on Route QL-13 near Base Area 708 in Cambodia allowed safeguarding supplies based out of a "neutral" location in order to reduce exposure to U.S. bombing.

[7]: 115–7 On 7 April, Gen. Minh reported to the National Security Council about the equivalent of four PAVN divisions in his Corps area, and demanded more troops to protect the road to Saigon.

Later in the day, the Council decided to assign the 21st Division from IV Corps as well as the 1st Airborne Brigade from JGS reserve to him.

[4]: 18  That evening, elements of the PAVN 9th Division overran Quần Lợi Base Camp, forced its defenders - the 7/5 Regiment destroyed their heavy equipment and fall back to An Lộc.

[6]: 119 Meanwhile, Task Force 52 abandoned their twin fire bases near the junction of routes QL-13 and LTL-17, destroyed their heavy equipment, broke the PAVN encirclement and moved southward on foot through the jungle to An Lộc.

The PAVN overwhelming forces quickly pushed the ARVN defenders back to the southern half of the city before being halted by massive airstrikes of B-52.

[7]: 121  Gen. Hưng, later ordered tank-destroying teams be formed by each battalion, which included PSDF members who knew the local terrain and could help identify strategic locations to ambush tanks.

The PAVN were concerned that because the ARVN 1st Airborne Brigade had air-assaulted into positions west of the city, that they were now coming to reinforce the defenders.

[6]: 152  During that day an A-37B piloted by First lieutenant Michael Blassie was shot down while providing air support, his body was recovered in late 1972 and he was separated from the identification documents recovered leading to him being later designated as the unknown service member from the Vietnam War buried at the Tomb of the Unknown Soldier at Arlington National Cemetery.

[6]: 157 On 13 May with intensive air support the 31st Regiment finally overran the PAVN positions and extended ARVN control to 8 km north of Chơn Thành.

On 17 June, the 48th Regiment of the 18th Division reoccupied Hill 169, allowing them to guide air and artillery strikes on PAVN forces.

[7]: 134–5  By 18 June 1972, the III Corps commander declared the siege was over and released the 1st Airborne Brigade to its parent unit.

[7]: 135  Despite this declaration, An Lộc remained under PAVN artillery fire, on 9 July Third [Military] Regional Assistance Command (TRAC) deputy commander Brigadier General Richard J. Tallman and his aides had just landed at An Lộc when they were hit by PAVN artillery fire, three of the group were killed instantly, while Tallman and two others were wounded.

On 8 August the 18th Division launched an assault to retake Quần Lợi, but was stopped by the PAVN in the base's reinforced concrete bunkers.

[6]: 198  Finally, the ARVN attacked the PAVN-occupied bunkers with TOW missiles and M-202 rockets, breaking the PAVN defense and forcing the remaining defenders to flee the base.

For the PAVN, it demonstrated their logistical constraints; following each attack, resupply times caused lengthy delays in their ability to properly defend their position.

[14]: 58–60 : 63–64  At this stage in the war, the PAVN often attacked with PT-76 amphibious and T-54 medium tanks spearheading the advance, usually preceded by a massive artillery barrage.

This was most probably a result of casualties sustained in the frustrated attacks on heavily entrenched enemy positions in control of a withering array of supporting firepower.