The operation was a qualified success in that it pushed the People's Army of Vietnam (PAVN) forces back across the Demilitarized Zone (DMZ).

During late June and early July 1966, Marine reconnaissance units operating south of the DMZ had observed and engaged increased numbers of uniformed regular PAVN troops.

[1]: 160  On 9 July a lieutenant from the 812th Regiment surrendered in the same area and advised that the 324B Division's mission was to "liberate" Quang Tri Province.

Company K continued on to their objective 1.8 kilometres (1.1 mi) south of LZ Crow, but they were repulsed by PAVN fire as they tried to cross the Ngan River, with the loss of three marines killed and five wounded.

The PAVN were now aware of the arrival of 3/4 Marines and the battalion started to come under sustained small arms, machine gun and mortar fire.

2/4 Marines set off at dawn towards 3/4's position and engaged the PAVN several times, calling in close air strikes, before linking up with 3/4 at 14:45.

[1]: 168–169  With the conclusion of Operation Deckhouse II on the morning of 18 July, 3/5 Marines would be inserted into a small valley 3 kilometres (1.9 mi) south of the Song Ngan in a suspected PAVN marshalling area.

At 14:00, 3/4 Marines began to move out, leaving Company K as a rearguard to provide security for the battalion CP and the engineers who were tasked with destroying captured ammunition and the three crashed CH-46s.

Company K's 1st Platoon bore the brunt of the assault and its squads were separated from each other as small groups of PAVN moved between them.

Captain Robert Modrzejewski, CO of Company K, and Sergeant John McGinty, commander of the 1st Platoon, were each awarded the Medal of Honor for their actions.

On the morning of 20 July following intense airstrikes, 2/4 assaulted up Hill 208, but found the heavily fortified position abandoned.

English also ordered 2/1 Marines to deploy and establish blocking positions at the western end of the valley 4 kilometres (2.5 mi) north of the Rockpile.

At that point Lance corporal Richard David Kaler immediately moved forward through the heavy fire and carried the fallen marine back.

On 22 July Kaler's platoon re-engaged the position and took heavy casualties and was pinned down by machine gun fire.

[2] On 24 July Company I, 3/5 Marines was setting up a radio relay station on Hill 362 approximately 7.5 kilometres (4.7 mi) north of the Rockpile.

As the 2nd Platoon moved to establish forward defences on the hillside the PAVN opened fire from concealed positions.

The PAVN then dropped accurate mortar fire on the crest of Hill 362 for the next two hours until a Marine UH-1E gunship from VMO-2 silenced them.

Company I was also battered by heavy rains from Typhoon Ora and this and the thick jungle canopy complicated the evacuation of wounded.

[1]: 173 On 25 July Kyle and English met at Dong Ha and decided to withdraw Task Force Delta to the south due to the difficult terrain for manoeuvre and the lack of LZs for helicopter assaults.

Walt described the PAVN troops encountered during Operation Hastings as follows: "We found them well-equipped, well-trained and aggressive to the point of fanaticism.