The successful defense allowed South Vietnamese forces to build up strength and then establish jumping off positions for their counteroffensive to recapture Quảng Trị Province.
The Marines destroyed 17 tanks and killed hundreds of PAVN before blowing up the bridge and falling back to form a defensive line northwest of Huế along the south bank of the Mỹ Chánh River.
His immediate task was to stabilize his forces and to make effective use of available American support through 1st Regional Assistance Command (FRAC) which had replaced the United States Army's XXIV Corps.
On the same date, President Nguyễn Văn Thiệu announced the appointment of Colonel Bui The Lan, as interim VNMC commander.
FRAC believed that the PAVN were capable of launching a new offensive in Thừa Thiên Province as the 304th, 308th and 324B Divisions, the 202nd and 203rd Armored Regiments and supporting units were all available for an assault.
[2]: 94 The 147th Brigade remained at Huế with the 4th and 8th Battalions, replacing personnel and making up supply losses sustained in the First Battle of Quảng Trị.
Due to the SA-7 antiaircraft missile threat, airborne Forward Air Controllers (FACs), forced to fly above 9,500 feet (2,900 m), could not readily spot enemy gun flashes.
With increasing forces available, Trưởng planned a series of limited objective attacks and raids to provide the South Vietnamese time to prepare for their counteroffensive and keep the PAVN off balance.
The first operation named Song Than 5-72 was to be a helicopter raid against PAVN positions in the Hải Lăng District southeast of Quảng Trị.
HMM-164 planned to provide the maximum possible lift capability in each wave and to reduce possible losses, the helicopter assault routes were flown Nap-of-the-earth contrary to then-current practice.
The joint efforts resulted in reports of 240 PAVN soldiers killed, three tanks destroyed and two 130 mm guns put out of action.
The PAVN attacked due south down the coastal highway, Route 555, (16°42′22″N 107°21′36″E / 16.706°N 107.36°E / 16.706; 107.36) moved across the Mỹ Chánh River and penetrated the 369th Brigade's defensive area.
After an all-day fight, however, the two battalions, assisted by close air strikes and ARVN armored cavalry, began pushing the PAVN back towards the Mỹ Chánh River.
Continuing their attack through the early morning darkness, the PAVN penetrated deeply into South Vietnamese territory, hitting the 369th Brigade's command post at first light.
A U.S. Army sergeant fired the BGM-71 TOW missile system from atop the command and control center bunker destroying a PT-76 and then a heavy machine gun nest.
[2]: 99–100 As the Marines consolidated and moved off the beach behind continuing air support and naval gunfire, the USMC amphibian tractors returned to the ships.
Two PAVN soldiers captured by the Marines stated that their regiment had just arrived in the area in preparation for an attack on the Mỹ Chánh Line.
[2]: 100 As air observers and FACs uncovered road and trail networks or spotted troop movements and vehicles, they would report them to the Marine defenders along the Mỹ Chánh Line.
As trails, supply points, and troop sightings were plotted and connected, a pattern soon developed showing lines of communication mainly from the Ba Long Valley towards Camp Evans.
[2]: 101–2 At 05:30 on 25 May, a numerically superior PAVN tank-infantry force hit the 258th Brigade in the western portion of the Marine division's large area of responsibility.
Although armor was employed in unprecedented numbers, the PAVN committed its infantry prematurely, exposing it to heavy supporting arms fire.
Heavy air strikes and naval gunfire was directed onto the attackers, who finally broke contact, leaving their dead where they had fallen.
[2]: 102–3 [3]: 57–60 On 31 May President Thiệu promoted Marine Division commander Colonel Bui The Lan to Brigadier General at the Imperial City, Huế.
The Marines moved forward under the cover of a closely coordinated fire support plan which included B-52 strikes, tactical air, artillery and naval gunfire.
The American-established FSCC at division headquarters permitted supporting arms to be fired in concert, a technique heretofore fraught with problems of execution.
[2]: 103–4 In order to consolidate the Marines' captured territory, ARVN engineers built pontoon bridges across the Mỹ Chánh River to give tanks, artillery, and trucks access to Quảng Trị Province.
Both tactical aircraft and naval gunfire supported the battalion as Lieutenant Colonel Do Huu Tung rallied his battered Marines for a tank and infantry counterattack.
[9] The probing attacks in June tested PAVN strength and allowed for the establishment of advance positions ahead of the launch of Trưởng's Operation Lam Son 72 to recapture Quảng Trị Province.
Throughout April, May and June more than 18,000 sorties by tactical aircraft had been flown, 45% by the USAF, 30% by the USMC and Navy and 25% by the Republic of Vietnam Air Force.
The official PAVN history records the battle as follows:[10]This was a great opportunity, but, because we lacked a reserve force and because we had not prepared roads and supplied beforehand, our troops were not able to take advantage of this opportunity to exploit our victory and liberate Thừa Thiên-Huế...The enemy focussed on consolidating his defensive line along the Mỹ Chánh River and used this line as a base to strike out to the east and west to disrupt our preparations to attack Huế...Our troops experienced many difficulties in maintaining supply levels and we were able to provide only 30 percent of the supplies called for in our plan.