In mid-May, General Simpson was briefed by Col. Charles S. Robertson, commander of the 1st Marines, on a campaign designed to deny the enemy continued safe-haven in the two areas. In his briefing Colonel Robertson stressed that Operation Pipestone Canyon was a natural sequel to Operations Taylor Common and Oklahoma Hills.

As planned, the operation would begin with two battalions, BLT 1/26 from SLF Alpha, and 3/5, attacking eastward into the operational area. Designed as a feint, these two battalions would then establish blocking positions. Once this had been accomplished, five battalions (1st and 2d Battalions, 1st Marines; 37th ARVN Ranger Battalion; and the 1st and 4th Battalions, 51st ARVN Regiment) would attack southward into and through Dodge City, then on into neighboring Go Noi Island. This movement would be executed in coordination with two Korean Marine Corps battalions holding positions on the southern edge of the AO. The effort would be a true allied operation.

The contiguous areas of Dodge City and Go Noi Island lay ten to twenty kilometers south of Da Nang and six to twenty kilometers west of Hoi An. The combined area was bordered on the west by the south fork of the Song Vu Gia; on the north by the Song Al Nghi, Song Lo Tho, and Song Thanh Quit; on the east by Route 1; and on the south by the Song Thu Bon, Song Ba Ren, and Song Chiem Son. A north-south railroad berm bisected the area. Most of the land was flat, but it was covered with rice paddies, thick brush, tangled hedgerows, and vast expanses of tall elephant grass. Nearly two dozen villages and hamlets dotted the region.

The morning of 26 May opened with a blistering bombardment of the AO's western region. Heavy 8-inch shells from the offshore USS Newport News and artillery fire from the cannons of 1/11 ripped into the terrain with an explosive fury. Following this bombardment, the members of Lt. Col. George C. Kliefoth's 1/26 and Lt. Col. Harry E. Atkinson's 3/5 stepped off on their eastward attack. The first few days of the movement resulted in only minor contact. However, as the Marines moved closer to Dodge City and Go Noi Island, enemy resistance picked up. By mid-afternoon on 30 May, the two battalions had set up their blocking positions just west of the railroad berm.  They had killed sixteen NVA but lost a total of ten dead and more than a hundred wounded. All the friendly casualties had been caused by mines or booby traps.

The next day the five allied battalions stepped off from their positions on the Song Lo Tho. The southward attack was preceded by an intense artillery and naval gunfire bombardment. As concussion waves rolled over the waiting riflemen, they hoped that the bursting shells would not only get the enemy soldiers but would detonate any mines and booby traps waiting for them. Soon after crossing the river, the lead rifle platoons started uncovering well-built bunker complexes generously salted with booby traps. These brutal devices would become even more prevalent the deeper the infantrymen drove into enemy territory. Actual enemy contact during the first few days, however, was light. All the evidence indicated that the enemy troops were fleeing to the south and west, toward the blocking force. Then, on 2 June, enemy resistance suddenly stiffened. Company G, 3/5, was hit by a shower of enemy mortars as it approached a small bunker complex. The company commander quickly ordered up a pair of the accompanying M48 tanks. After the armored giants, had pumped more than a dozen deadly 90mm shells into the heart of the enemy position, the riflemen attacked. The tanks had done their job well. Only a handful of enemy soldiers resisted the Marines. In minutes, it was over. Seven NVA lay dead and one wounded enemy soldier was captured.

Three days later the attackers reached the Song Ky Lam, which divided Dodge City from Go Noi Island. With the second phase of Pipestone Canyon over, the attacking forces paused to re-supply and reposition themselves for the third phase. During this interim period, Marine jets pounded Go Noi Island with an unrelenting fury. More than 750,000 pounds of high-explosive bombs chewed up the ground in front of the attackers.

The new phase began on 10 June. While General Simpson and the new 1st Marines commander, Col. Charles E. Walker, watched from a command post atop Hill 119 just south of Go Noi Island, twenty-two helicopters carried in Marines from 2/1 and a force of Korean Marines. The CH46s touched down unmolested in two LZs on the southern edge of Go Noi Island. Once formed, the combined force began sweeping north. That same afternoon the rifle companies of 1/1 began moving eastward from the Liberty Bridge area.

Once again, enemy contact proved light. The Viet Cong and NVA were scattering, breaking into small groups and sneaking past the advancing attackers to head south into the Que Son Mountains. Occasional brief firefights did break out, but these were mostly the futile efforts of small stay-behind forces. Several prisoners were taken, but they were primarily wounded or nearly starved enemy soldiers.

By l3 June, the major sweeps had been completed. While the allied battalions established company-sized AOs, the Provisional Land Clearing Company moved into eastern Go Noi Island. Equipped with a wide variety of bulldozers and tractors, the provisional company began plowing up eastern Go Noi. Able to clear 250 acres at a time, the company would eventually level more than eight thousand acres on the island, denying the enemy a major sanctuary.

While the bulldozers turned the soil on eastern Go Noi Island, the 1st Battalion, 1st Marines turned its attention to the western portion of the island. At dawn on l9 June, Company C headed west from the railroad berm. Within a short time, the deep karumph of an exploding booby trap shattered the morning. That one was soon followed by a second, then a third, then a fourth. It seemed that whichever way the Marines moved, the enemy had sown an explosive device. To reduce the frustration of dealing with these hidden killers, the battalion peppered its forward areas with artillery and an aerial bombardment. Infantry units took to riding atop tanks. But there was no way to completely avoid the antipersonnel devices. Only a constant state of awareness could combat the deadly mines.

After sweeping to An Quyen, 1/1 was replaced by 2/1 on 2lJune. Determined to clear western Go Noi of the enemy, the fresh Marines conducted daily search and clear operations. As had the Marines before them, the men of 2/1 found few enemy troops but many booby traps.

Company G had it particularly tough. Fifty-nine of the seventy dead and wounded that it suffered during this period resulted from booby traps and mines. As Capt. Frank H. Adams pointed out, the threat of death or injury from these devices severely demoralized the troops. 'It gets to the point', he said, 'where each individual says, 'They put them out there, we have got to sweep ... ultimately I'm going to hit one.' When you get to that point, as a leader you're lost'.

After a particularly bad day with booby traps, Adams had to pull his company off the line to give them a pep talk. It went surprisingly well. He finished up with a prayer and returned to the sweeps. The upturn in morale made him tremendously proud to be a Marine.

By late June, General Simpson had decided that eastern Go Noi would be permanently occupied. The 3d ARVN Battalion, 51st Regiment, and the 1st Battalion, Korean Marine Corps would occupy two new combat bases that covered the eastern portion of Go Noi. At least one U.S. Marine rifle company would patrol the island's western half.

For the rest of June and into early July, enemy activity waned in the Pipestone Canyon AO. Then, intelligence reports indicated that the enemy had returned to eastern Dodge City. On 14 July, elements of 2/1 air-assaulted into four landing zones in that area. As the troop' laden CH-46s came into the LZs, all took heavy enemy fire. Seven were hit and one was forced to make an emergency landing; fortunately, it was near a Korean Marine position. At two of the LZs the enemy fire was so strong that the helicopters were forced to divert to alternate landing zones. This caused a one-hour delay in establishing a cordon around the abandoned village of Tay Bang An, which was believed to harbor the enemy.