Mobile Riverine Force (MRF) in conjunction with various units of the Army of the Republic of Vietnam (ARVN) in late July 1967 in an attempt to shut down Viet Cong (VC) strongholds in the Mekong Delta.

At 02:00 on 27 July riverine assault craft began leaving the base for minesweeping and patrol stations along the route to Đồng Tâm.

Because of the slow speed of the towed APL moving against the tide the journey took almost 12 hours, but did not delay the commencement of the new operation in Định Tường Province on 28 July.

[1]: 120 On 27 July the ARVN 7th Division initiated operations designed to sweep for VC from east to west, north of Highway 4.

The ARVN 7th Division was given the 44th Ranger Battalion by the commander of South Vietnam's IV Corps for insertion by helicopter into the northwestern portion of Cam Son on 28 July.

[1]: 121 The MRF operation in Cam Son began during the evening of 28 July with the movement of the 5/60th Infantry, from its Long An base camp along Highway 4 to the town of Cai Lậy.

The troop had a reconnaissance mission covering eastern Cam Son and western Ban Long on the brigade's flank.

[1]: 121  Throughout the late morning on 29 July both the 3rd and 4th Battalions, 47th Infantry Regiment, discovered widely dispersed small groups of VC.

As the 3/47th Infantry moved companies into this area from the north and south on the east bank of the Rach Ba Rai, the VC resisted.

For five hours the Marines attacked prepared VC defensive positions, who fired light and heavy machine guns and mortars.

In mid-afternoon General O'Connor directed Colonel William B. Fulton, commanding officer of the 2nd Brigade, to assist the 3rd Marine Battalion in evacuating casualties and preparing for an attack against the VC.

[1]: 123 During the action on 29 July, several ATCs were hit with small arms, rocket, and recoilless rifle fire, none suffered major structural damage.

During the morning of 31 July, the 3/39th Infantry was placed under the operational control of Colonel Fulton, bringing the MRF to four battalions and Troop D, 3/5th Cavalry.

[1]: 124 Colonel Fulton directed the 3/39th Infantry, to conduct reconnaissance using helicopters southeast of the battle area and moving west to Ap Binh Thoi.

One American company moved out to search northwest of the town while the rest of the battalion assisted the Vietnamese police in apprehending and interrogating people suspected of being VC.

The Americans said that this was "primarily because of the outstanding performance of the 3rd Marine Battalion...[who] destroyed major fortifications in the Cam Son base area, probably thwarted planned enemy operations against Đồng Tâm, and eased the pressure on Highway 4.

[1]: 125 This article incorporates public domain material from websites or documents of the United States Army Center of Military History.