July 2018

Radio Battalions in Vietnam During Operation Dewey Canyon

Volume 101, Issue 7

Sara W. Bock

Sara W. Bock
Intelligence gathered throughout Operation Dewey Canyon was crucial to its success. Here, members of 9th Marines inventory weapons and ammunitions captured during the operation in the largest haul of enemy supplies taken during the war.

The most successful offensive operation in Vietnam occurred in early 1969, about a year before the Marines started to withdraw from that long ago war in a faraway clime and place. Named Operation Dewey Canyon, it was hardly surprising that the Marines were so stunningly triumphant. Marine success was built on a solid foundation—senior commanders who understood and knew how to use intelligence—and a very professional group of little-known but highly effective noncommissioned and staff noncommissioned officers.

Operation Dewey Canyon was supported by a largely unknown and still highly secretive unit of Marines—the 1st Radio Battalion. Major Alfred M. “Al” Gray, future 29th Commandant of the Marine Corps, had led an intelligence unit reinforced by a rifle company into Vietnam almost a year before large Marine combat units arrived in March of 1965. By 1967, under the leadership of then-Lieutenant Colonel Gray, the “spooks” had come into prominence. In the run up to the Tet Offensive of 1968, Gray’s Radio Battalion (RADBN) knew full well where and how the enemy would attack across I Corps. Senior Marine leadership became increasingly confident in the ability and usefulness of the well-trained, albeit mysterious, intelligence unit.

Throughout the latter part of 1967 and all of 1968, Marine combat units in Vietnam had been largely tied to fixed bases. The infamous McNamara Line, named for the then-Secretary of Defense, had been built across northern I Corps and while designed to be an electronic barrier to stop North Vietnamese infiltration into the South, in reality it did little more than tie Marines to a series of combat bases. This disposition led to artillery duels and the famous Battles of Khe Sanh and Dai Do, among others. It was not how the Corps, and particularly Major General Ray Davis, the commanding general of 3rd Marine Division, wanted to fight. MajGen Davis intended to get the 3rdMarDiv away from their bases and take the offensive.

Davis’ plan was to attack enemy units by displacing artillery to within easy supporting range of helicopter-borne infantry. Davis had spent time as a deputy to Lieutenant General Richard Stilwell and the Army’s 24th Corps and had learned much about how that service employed its helicopters. He was determined to use all of his available combat power in much the same way.

Timely, pertinent intelligence played a significant role in the success of the operation. Marine Signal Intelligence/Electronic Warfare/Signal Security (SIGINT/EW/ SIGSEC) units had been re-established in the mid-1950s and Marine Communications Intelligence (COMINT), known as radio intelligence platoons, employed during World War II to support naval operations, had been disbanded after the war. There was no such Marine capability for the Korean War. Plans for Marine SIGINT/EW/SIGSEC units, called radio companies and later radio battalions, were approved as a result of Major General Robert Hogeboom’s study to shape the future Corps in 1954. The next year, one of the first officers selected to serve in the SIGINT field was First Lieutenant Al Gray. During the late 1950s, Gray led numerous SIGINT detachments in direct support of brigade and force exercises in the Pacific. Many Marine generals came to learn the value of using SIGINT/SIGSEC to support operations.

Resistance to SIGINT’s direct ties to combat units remained powerful within the Corps throughout the 1960s and even into the 1970s. For example, then-Brigadier General Leonard F. Chapman, the future 24th Commandant of the Marine Corps, refused to hold the special security clearances needed for access to SIGINT information for fear it might preclude him from holding higher combat-related commands. Throughout the Vietnam War, only infantry commanding officers and very limited numbers of staff officers and staff noncommissioned officers were given the necessary clearances. Information about the radio battalion and its mission and capabilities was not taught at The Basic School or any of the various SNCO and NCO academies. What “spooks” did was very much unknown to most Marines, and most “spooks” liked it that way. The majority of cryptologic officers and noncommissioned officers not only preferred hiding behind their inscrutable ways and mysterious methods but also reveled in the concept of being “behind the green door.” Few outside the SIGINT community had knowledge of or control over them.

When Maj Gray assumed command of 1st Radio Bn in Da Nang in July 1967, much changed. Lieutenant General Robert E. Cushman, the commanding general of the 3rd Marine Amphibious Force, was an intellectual who knew SIGINT. Cushman had observed Maj Gray’s work at Headquarters Marine Corps in the early 1960s and knew of Gray’s deep ties to SIGINT. In addition, throughout his time with the 12th Marine Regiment in Vietnam (1955-1957), Gray had served as an unofficial advisor on special intelligence matters, including evaluating and processing SIGINT, to the III MAF commander—first to LtGen Lewis Walt and then subsequently to LtGen Cushman. Additionally, he provided similar support to his 3rdMarDiv commanders, Major General Kyle and MajGen Hochmuth. Despite the fact that Gray had been promised command of an infantry battalion when he voluntarily extended his combat tour for a third time, Cushman had other ideas and sent his subordinate to command 1st Radio Bn. Characteristically, Gray threw himself into full-time intelligence work and changed how the RADBN conducted its business.

Gray aggressively pushed to provide direct support to combat units. RADBN operators—usually sergeants or corporals—were directed to provide all assistance possible to unit commanders located within close proximity to various RADBN detachments spread throughout I Corps. This close liaison occurred often without the combat Marines learning sources and methods. The supported units, however, quickly came to realize that if the spooks offered intelligence about the NVA, it probably was right.

Gray also enabled SIGINT to work closely with all other MAF and Division intelligence units and ensured that all Army intelligence activities, fixed sites and the local aviation company worked together to produce a unified, single assessment of enemy activity. Intelligence was closely integrated with operations. The culmination of the operations-intelligence teamwork resulted in the Marines breaking the Viet Cong and NVA codes in the late summer and early fall of 1967. It was a gigantic intelligence coup.

Gray left Vietnam on emergency leave in January 1968 but the RADBN continued to directly support Marine ground forces. When MajGen Ray Davis arrived at the 3rdMarDiv in May 1968, he set about changing how the Division operated. Davis, like Cushman, was very familiar with SIGINT. As a colonel, he had met then-Captain Al Gray in Japan in the 1950s. Their relationship continued throughout Davis’ career and into retirement. There was no reluctance on the part of the commanding general to use SIGINT.

Much of what the RADBN exploited was limited by distance from the targets and the terrain. By embedding spooks with artillery units—sometimes even in infantry units—as they displaced throughout the battleground, any enemy activity detected nearby could be fully and rapidly exploited. Gunnery Sergeant William I. Jones, Staff Sergeant Paul Plante, and Corporal John House were three of the Vietnamese linguists attached to the 9th Marines. Typically, they were co-located with a battalion headquarters, or they were positioned near the command post.

Accompanying each Marine linguist was a soldier from the Army of Republic of Vietnam (ARVN), who assisted the Marine in interpreting and transcribing what was heard. Corporal Tinh was Plante’s constant companion. Tinh was also a dedicated professional whom Plante admired and respected highly. By this time in the war, RADBN teams were exploiting NVA communications fully. Not surprisingly, both the RADBN Marines and their ARVN cohort were well accepted by Barrow’s warriors. During Dewey Canyon, either Plante or Tinh manned their PRC-25 around the clock. The most significant low-level communications the Marines intercepted reflected NVA fire control coordination or other low-level infantry talk. It was the RADBN fixed direction-finding sites throughout northern I Corps that found high-level NVA communications, and then pinpointed the location of sub-units and sub-sub-units. The voice communications, always very short range, were from these lower level units.

While Plante and the others passed their information directly to the operations officer, operations chief or intelligence officer or chief, combat Marines quickly learned to “read the signs.” For example, if the spooks suddenly appeared wearing flak jackets and helmets, those close realized enemy mortar or artillery attacks might be imminent. Or highly perishable information derived from communications might be disguised as the results of direction finding. At the height of the operation, the RADBN teams might provide several warnings per day. Everyone involved realized these warnings saved Marine lives. And as a result, in later years both Davis and Barrow reported that they “could finally fight the enemy and not the terrain.”

Interestingly, when Davis returned home and became the commanding general of the Education Center in 1970, the Marine Corps dispatched him on an extended public relations tour around the country. Davis briefed various audiences about combat operations in Vietnam. He selected a young lieutenant colonel, a student at the Command & Staff College, to accompany him and give an “intelligence assessment.” The student was Al Gray.

Operation Dewey Canyon and the support provided by the RADBN Marines also provided the impetus to the eventual formation of the Radio Reconnaissance Teams and Radio Battalion Detachments becoming integral parts of all Marine Expeditionary Units (Special Operations Capable) in the late 1980s. Importantly, Marine combat units and attached RADBN elements continued to hone their relationship during the battles in Iraq and Afghanistan. Evidence that the Marine Corps had overcame any resistance to having spooks in large numbers was reflected when 3rd Radio Bn was activated in 2003.

Mr. Laidig was a platoon leader with 2/4 from 1966–67. He is the author of Al Gray, Marine (Potomac Institute Press, 2012).