Vietnam War: Operation Dewey Canyon

By Marc Bernstein | Vietnam  | 4 comments  |  Print This Post  |  Email This Post

The 9th Marines were well prepared to launch this operation, as they had spent the previous eight months honing their mountain warfare skills in combat in Quang Tri Province. However, the operational planning was a hurry-up affair. As Barrow remarked later, “Dewey Canyon was planned, including command reconnaissances and support arrangements, and launched in five days.” Nevertheless, he said, “The force that entered Dewey Canyon was about as ready as any force could possibly be.”

Dewey Canyon would be a three-phase operation. In Phase I, the regiment would move into the area of operations and establish fire support bases for the supporting artillery of the 2nd Battalion, 12th Marines (2/12). Phase II would consist of patrolling near the fire support bases and aligning the infantry units for a jump-off into the next phase. Phase III called for a conventional three-battalion advance southward, with the infantry units moving overland rather than by helicopter because heavy anti-aircraft defenses in the area of the Phase III objectives made movement by foot preferable to General Davis’ usual concept of high-mobility heliborne operations. But because the area was in the remote southwest corner of Quang Tri Province, helicopters would still be critical in the early phases and in resupplying the troops on the ground.

The upper Song Da Krong Valley is 62 kilometers west of Hue and 48 kilometers southwest of Quang Tri City, and the 9th Marines would be operating some 50 kilometers south of their main supply depot at Vandegrift Combat Base. The valley follows the course of the winding Da Krong River (Song Da Krong) and is surrounded by high mountains and ridgelines. Between it and the neighboring A Shau Valley to the south are two large hill masses, Tam Boi (Hill 1224) and Co A Nang (Hill 1228), the latter better known as Tiger Mountain. On the western edge of the valley stands a 1,500-meter-high razorback ridge named Co Ka Leuye. The eastern half of the valley is covered with dense jungle, while west of the river it is dominated by tall elephant grass and brushwood. The river itself runs east to west, then makes a sharp turn to the north.

Phase I began on January 19 with the reopening of Fire Support Base Henderson, eight kilometers southeast of Ca Lu. The next day, fire support bases Shiloh and Tun Tavern, which had been used by the 9th Marines in earlier operations, were reopened. On January 22, 2nd Battalion, 9th Marines (2/9) air-assaulted into the northern sector of the Dewey Canyon area of operations to establish Fire Support Base Razor, eight kilometers south-southeast of Shiloh, near the Da Krong River. In order to construct Razor, large trees had to be felled and bulldozers were brought in by helicopter to clear the area and prepare it for the insertion of artillery. On January 24, the 3/9 air-assaulted onto a razorback ridgeline about six kilometers south-southeast of Razor to build Cunningham and begin patrolling in the vicinity. Cunningham became the center of the Dewey Canyon operation as two batteries of 2/12 moved into it to complete Phase I. The Dewey Canyon area of operations was now well covered as the effective range of the artillery at Cunningham was 11 kilometers. Eventually the 9th Marines’ command post and that of the 2/12 moved to Cunningham to take advantage of its central location.

Enemy opposition to Phase I had been light. Accordingly, Phase II began without difficulty on January 24-25, when the 2nd and 3rd Battalions started intensive patrolling north of the Da Krong River. Almost immediately, 3/9 uncovered a four-strand North Vietnamese Army telephone line strung between trees running from Laos into enemy Base Area 101 farther east within South Vietnam. A special communications intelligence team was quickly brought in to tap the wires and break the code. A North Vietnamese hospital consisting of eight large permanent buildings—Field Hospital 88—near the Da Krong River, was discovered by 2/9. The complex, abandoned just a day before the Marines found it, contained large quantities of Russian-made surgical instruments and antibiotics.

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Tags: Historical Conflicts, Vietnam War

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