The Vietnam War was characterized by numerous military campaigns and operations, but Operation Dewey Canyon stands out as one of the significant engagements by the United States Marine Corps. In the latter stages of the conflict, particularly throughout 1967 and 1968, Marine units in the northern I Corps region of South Vietnam had been tethered to combat bases along the border in alignment with the strategic defensive blueprint known as the McNamara Line. This system – a meld of infantry hubs and electronic ground sensors – was devised with the intent to stymie the North Vietnamese Army (PAVN) infiltration into South Vietnamese territory via the concealed routes of the Ho Chi Minh Trail. However, the stationary and defensive posture required by the McNamara Line contrasted sharply with the traditional and aggressive combat style historically favored by the Marines.

Upon assuming the helm of the 3rd Marine Division, Maj. Gen. Raymond G. Davis spearheaded a strategic pivot. He sanctioned an operational shift, directing Marine forces to vacate their static roles within combat bases and instead actively engage the enemy forces in their own domains. Maj. Gen. Davis's directive was indicative of a broader tactical evolution, embracing mobility and offense over fortified defense.

Operation Dewey Canyon

Initially Christened as Operation Dawson River South, the operation unfurled in three concentrated phases. The initial move saw the southward deployment of the 9th Marines and supporting arms to establish a network of firebases endowed with mutual support capabilities in proximity to the target zone. Subsequently, a period of intensive reconnaissance patrolling around these bases ensued, preluding the final stage wherein the Regiment would launch an offensive into the heartland of the PAVN bases.

Operational synergy was meticulously crafted with coordinated actions involving the 101st Airborne Division and the South Vietnamese Army (ARVN) 2nd Regiment, 2nd Division to reinforce efforts east of the A Shau Valley. General Davis would emphatically convey that the salient objective of the operation was to disseminate PAVN logistic networks rather than to engage combatant forces directly. He stated, "There was no [PAVN] force down there, we knew that. Our primary target was to go in and ferret out this system - without any thought that there was a major force down there."

Top photo: Leathernecks of the 2d Battalion, 9th Marines [2/9] trudge across a mountain stream in search of the enemy during Operation Dewey Canyon in the northern A Shau Valley complex (official USMC photo by Lance Corporal Bill Carroll). From the Jonathan F. Abel Collection (COLL/3611), Marine Corps Archives & Special Collections, Quantico, Virginia. OFFICIAL USMC PHOTOGRAPH. Click to enlarge.

Bottom photo: After the Battle: Men of the 4th Marines move along a ridgeline following a battle with a well entrenched North Vietnamese force near the Demilitarized Zone. The Marines killed 31 of the enemy and unearthed large caches of enemy supplies and ammunition (official USMC photo by Lance Corporal M. C. Patterson). From the Jonathan F. Abel Collection (COLL/3611), Marine Corps Archives & Special Collections, Quantico, Virginia. OFFICIAL USMC PHOTOGRAPH. Click to enlarge.

Between 22 January and 18 March 1969, over the span of 56 grueling days, Operation Dewey Canyon unfolded as a tactical expedition highlighted by ferocious combat and strategic acumen. Despite the initiative being touted as a tactical success, it did not comprehensively halt the entrenched stream of North Vietnamese troops and supplies flowing into South Vietnam.

Phases of Operation Dewey Canyon

The tactical execution of Operation Dewey Canyon can be demarcated into three distinct phases designed to mitigate the mobility of the PAVN and curtail their logistical operations.

Phase One: This initial phase was characterized by the strategic establishment of firebases by the 9th Marines. These bases, situated at tactical vantage points, provided critical support for troops and served as platforms for artillery and aerial operations against the PAVN. It was a move aimed at cementing the U.S. military's presence and creating a foundation for sustained offensive maneuvers in the region.

Phase Two: The ensuing phase involved exhaustive reconnaissance within the operational vicinity. Marines conducted thorough patrolling to ascertain PAVN movement patterns and identify crucial supply routes. This reconnaissance was integral to the mapping of enemy strongholds and paved the way for the impending direct offensive.

Phase Three: The final phase saw the culmination of previous efforts as the 9th Marines launched an extensive thrust into PAVN-occupied territories. Mounting a fierce incursion into enemy strongholds, the forces sought to dismantle the infrastructure supporting the PAVN war effort. Extensive air support and artillery bombardment were synchronized with the ground assault, ensuring a concentrated and effective strike on the logistical lifelines of the North Vietnamese forces.

The human toll on the Marines was significant – with 130 lives lost and 932 wounded. Conversely, they reported neutralizing 1,617 PAVN soldiers and seizing approximately 500 tons of weaponry, artillery, and munitions. The process effectively impeached the valley as a PAVN staging ground while the operation persisted. However, these gains proved ephemeral, as Base Area 611 experienced a resurgence of PAVN activity, compelling the 101st Airborne Division to launch Operation Apache Snow in the same region two months later.

Despite the seemingly limited success of Operation Dewey Canyon, it had far-reaching implications for the future conduct of military operations in Vietnam. The operation demonstrated the effectiveness of coordinated efforts and strategic planning in disrupting enemy supply lines and hampering their ability to reinforce combatant forces. Additionally, General Davis' emphasis on civilian pacification and winning hearts and minds served as an influential model for

Notwithstanding the intense struggle and its fleeting victories, the bravery and excellence of the U.S. forces were formally recognized. The 9th Marine Regiment, along with attached units, received the esteemed Army Presidential Unit Citation for their gallant performance. Individual acts of valor were acknowledged with the awarding of four Medals of Honor, six Navy Crosses, and 55 Silver Stars, bearing testimony to the grit and determination shown throughout Operation Dewey Canyon.

Bibliography

Karnow, Stanley. Vietnam: A History. New York, N.Y., U.S.A.: Penguin Books, 1984.

Woods Eisenberg, Carolyn. Fire and Rain: Nixon, Kissinger, and the Wars in Southeast Asia. New York: Oxford University Press, 2023.

Rayburn, Major USMC, James S. "Direct Support during Operation DEWEY CANYON." U.S. Department of Defense. https://media.defense.gov/2021/Jun/30/2002752776/-1/-1/0/DIRECT%20SUPPORT.PDF.