U.S. involvement in the Vietnam War escalated from 1960 under President John F. Kennedy, with troop levels gradually surging from just under a thousand in 1959 to 16,000 in 1963.

[5]: 119 On 20 January People's Army of Vietnam (PAVN) artillery and rockets firing from across the Vietnamese Demilitarized Zone (DMZ) hit Camp Carroll causing little damage.

At 13:30 on 24 January elements of the PAVN 320th Division ambushed a Marine "Rough Rider" convoy on Route 9, 3 km (1.9 mi) from Camp Carroll (16°47′24″N 106°55′52″E / 16.79°N 106.931°E / 16.79; 106.931).

The PAVN were ready for the reaction force and immobilized the lead M48 with recoilless rifle fire killing the company commander.

On the afternoon of 14 February after completing an unsuccessful search for suspected PAVN mortars on the high ground in the hills 3 km west of Ca Lu Combat Base, Company K, 3/9 Marines had started down towards Route 9.

[5]: 235 [6][7] On 28 February PAVN antiaircraft fire shot down a Marine CH-46 near Ca Lu Combat Base killing all 22 passengers and crew.

May–June saw minimal PAVN activity with occasional mines and small ambushes along Route 9 and rocket attacks on Camp Carroll and LZ Stud.

In late June control of the Lancaster sector passed briefly to Task Force Hotel commanded by BG Carl W.

1/3 Marines swept the area over the next 4 days locating abandoned PAVN positions and suffering loses due to sniper fire and command-detonated mines before returning to LZ Stud on 15 July.

Also on 25 July BLT 2/4 Marines was landed on Hill 679 12 km west of LZ Stud to patrol the area to the north.

[8]: 233  After securing Hill 606 2/4 Marines then searched the Khe Giang Thoan Valley locating PAVN rocket launch site and destroying 20 tons of supplies.

Denied permission to enter the DMZ the Marines swept the area locating PAVN bunkers and supplies including 2 75mm pack howitzers.

[8]: 155  The unnamed "July Action" operation concluded on 3 August and was regarded as a success as the Marines adopted new more mobile tactics aimed at disrupting PAVN supply lines rather than being tied to the defense of large bases along the DMZ.

[5]: 364–8 From September to November apart from mines on Route 9 and the occasional mortar attack on the large bases, most of the PAVN activity in the Lancaster area was centered on Landing Zones Mack and Sierra on Mutter's Ridge.