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Operation Market Time
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| Operation Market Time | |||||
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| Part of the Vietnam War | |||||
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| Belligerents | |||||
 South Vietnam United States Australia |
 North Vietnam Viet Cong | ||||
Operation Market Time was the United States Navy, Republic of Vietnam Navy and Royal Australian Navy operation begun in 1965 to stop the flow of troops, war material, and supplies by sea, coast, and rivers, from North Vietnam into parts of South Vietnam during the Vietnam War. Also participating in Operation Market Time were United States Coast Guard's Squadron One and Squadron Three. The U.S. Coast Guard operated, under U.S. Navy command, heavily armed 82-foot (25 m) patrol boats and large cutters armed with 5-inch naval guns, which were used in battle and gunfire support.
Radar picket escort ships, based in Guam or Pearl Harbor, provided long-term presence at sea offshore to guard against trawler infiltration. Originally built for World War II convoy duty, and then modified for distant early warning ("DEW") duty in the North Atlantic, their sea keeping capability made them ideal for long-term presence offshore where they provided support for Patrol Craft Fast (PCF) boats, pilot rescue and sampan inspection. There were two or three on station at all times. Deployments were seven-months duration, with a four- or five-month turn-around in Pearl. When off station, they alternated duty as Taiwan Defense Patrol, with stops in Subic and Sasebo for refit mid-deployment.
Operation Market Time was one of six Navy duties begun after the Tonkin Gulf Incident, along with Operation Sea Dragon, Operation Sealords, Yankee Station, PIRAZ, and naval gunfire support.
Background
[edit]When a trawler was intercepted landing arms and ammunition at Vung Ro Bay in northern Khánh Hòa Province on 16 February 1965, it provided the first tangible evidence of the North Vietnamese supply operation. This became known as the Vung Ro Bay Incident.[1] Operation Market Time was established by the United States Joint Chiefs of Staff at the request of General William C. Westmoreland, commanding general of Military Assistance Command Vietnam. He requested that the U.S. Navy establish a naval blockade of the vast South Vietnam coastline against North Vietnamese gun-running trawlers.[2] The trawlers, usually 100 feet (30 m) long Chinese-built steel-hulled coastal freighters, could carry several tons of arms and ammunition in their hulls. Not flying a national ensign that would identify them, the ships would maneuver "innocently" out in the South China Sea, waiting for the cover of darkness to make high-speed runs to the South Vietnam coastline. If successful, the ships would off load their cargoes to waiting Việt Cộng (VC) or People's Army of Vietnam (PAVN) forces.
At the time of inception, the Coast Guard contributed seventeen 82 feet (25 m) Point-class cutters while the Navy added approximately fifty ships known as Patrol Craft Fast (PCFs or Swifts) that could reach a maximum speed of 28 knots.[3] In detail, on 16 April 1965 United States Secretary of the Navy Paul Nitze requested Coast Guard assistance with Market Time. On 6 May 1965, the seventeen Point-class cutters were loaded as deck cargo on merchant ships in New York City, Norfolk, New Orleans, Galveston, San Pedro, San Francisco and Seattle for transport to U.S. Naval Base Subic Bay. At Subic Bay each of the cutters was armed with an 81 mm mortar and five .50 caliber machine guns. Coast Guard Squadron One was organized into Division Eleven with eight of the cutters and Division Twelve with nine of the cutters. Division Twelve sailed on 15 July 1965 and arrived at Đà Nẵng on 20 July. Division Eleven sailed on 20 July and arrived at An Thoi on 31 July. An additional nine cutters were provided to form Division Thirteen at Vũng Tàu in early 1966. Each cutter with an eleven-man crew would spend four days on patrol followed by two days alongside a support ship. All 26 cutters were turned over to South Vietnamese crews between 16 May 1969 and 15 August 1970.[1]
Operations
[edit]Coastal surveillance centers
[edit]In an effort to coordinate all coastal interdiction activities, coastal surveillance centers (CSC) were established at Da Nang, Qui Nhon, Nha Trang, Vung Tau and An Thoi and were manned by Republic of Vietnam Navy (RVNN) and U.S. Navy watchstanders. Reports of possible sightings of suspect vessels from aircraft and watercraft were reported to the CSC's and the appropriate response vessels and aircraft were dispatched to the scene by CSC personnel.[4][5]
Watercraft
[edit]_refuels_from_USS_Guadalupe_(AO-32)_during_a_Market_Time_patrol_off_Vietnam,_in_1968-1969_(6309).jpg)
The objective of Operation Market Time focused on preventing communist ships from infiltrating the South Vietnamese coast to resupply PAVN/VC forces. Beginning officially on 11 March 1965, Market Time featured a picket line of ships along over 1,000 miles (1,600 km) of South Vietnamese coast including forces from the U.S. Coast Guard, the U.S. Navy and the RVNN.[6] The operation was originally placed under the control of the Vietnam Patrol Force (Task Force 71). Command shifted to the Commander, Naval Forces Vietnam on 31 July 1965 and designated as Task Force 115.[7] Operation Market Time was originally planned to acquire 54 Swift boats, but that number increased to a total of 84 in September 1965 to thoroughly guard the coast of South Vietnam. These Swift boats were further separated into five groups and assigned to different areas of operation including Division 101 located at An Thoi (working alongside Coast Guard Division 11), Division 102 at Da Nang (with Coast Guard Division 12), Division 103 at Cat Lo (with Coast Guard Division 13), Division 104 based at Cam Ranh Bay and Division 105 at Qui Nhon.[8]
Seaplane tenders USS Currituck, USS Pine Island and USS Salisbury Sound served as flagships for Market Time.
U.S. Navy Martin P-5 Marlin seaplane patrol squadrons, destroyers, ocean minesweepers, PCFs and United States Coast Guard cutters performed the operation. Also playing a key role in the interdictions were the Navy's patrol gunboats (PGs). The PG was uniquely suited for the job because of its ability to go from standard diesel propulsion to gas turbine (turboshaft) propulsion in a matter of a few minutes. The lightweight aluminum and fiberglass ships were fast and highly maneuverable because of their variable-pitch propellers. Most of the ships operated in the coastal waters from the Cambodian border around the south tip of Vietnam up north to Đà Nẵng. Supply ships from the Service Force, such as oilers, would bring mail, movies and fuel.
A significant action of Market Time occurred on 1 March 1968, when the North Vietnamese attempted a coordinated infiltration of four gun-running trawlers. Two of the four trawlers were destroyed by allied ships in gun battles, one trawler crew detonated charges on board their vessel to avoid capture, and the fourth trawler turned tail and retreated at high speed into the South China Sea. LT Norm Cook, the patrol plane commander of a VP-17 P-2H Neptune patrol aircraft operating from Cam Ranh Bay, was awarded a Distinguished Flying Cross for discovering and following two of the four trawlers in the action.
Of the many vessels involved in Operation Market Time, one of the more notable was the USCGC Point Welcome which, on 11 August 1966, was brought under fire by a number of United States Air Force aircraft. This incident of a "blue-on-blue" engagement killed two members of the cutter's crew (one of whom was the commanding officer) and wounded nearly everyone on board.[9]
Aircraft
[edit]
To stop these infiltrations, Market Time was established as a coordinated effort of long range patrol aircraft for broad reconnaissance and tracking. These aircraft, initially SP-5B seaplanes, later P-2 Neptunes and Lockheed P-3 Orions, were armed with Bullpup air-to-surface missiles were capable of engaging these craft directly. Under normal conditions, U.S. and allied surface forces intercepted suspect ships that crossed inside South Vietnam's 12-mile coastal boundary. On the aviation side, some of the patrol squadrons that were involved and flying from South Vietnam, Thailand, or Philippine bases were: VP-1, VP-2, VP-4, VP-6, VP-8, VP-9, VP-16, VP-17, VP-19 VP-22, VP-26, VP-28, VP-40, VP-42, VP-45, VP-46, VP-47, VP-48, VP-49 and VP-50.
Aircraft flew constant and monotonous patrols along 1,200 miles (1,900 km) of coast during Operation Market Time departing from bases ranging from Vietnam (Tan Son Nhut Airbase and Cam Ranh Bay) to the Philippines (Sangley Point) and Thailand (Utapao Airbase). Although the air support missions received little press coverage, their importance to the overall operation cannot be denied. Planes had the ability to cover large expanses of water in a relatively short time and could monitor suspicious vessels lingering in international waters waiting to make a dash for the coast.[10] By October 1967 air surveillance expanded to monitor traffic bound to and from Cambodia as at this point it had become apparent that communist supplies were being shipped to Sihanoukville which were then transported over to the South Vietnamese border in large convoy trucks.[11]
Aftermath
[edit]Market Time, which operated day and night, fair weather and foul, for eight and a half years, denied the North Vietnamese a means of delivering tons of war materials into South Vietnam by sea. Nonetheless, assessing the overall effectiveness of Operation Market Time is problematic for several reasons. The operation cannot be considered a failure in any sense, but debate over its success continues. The Navy's Operations Evaluation Group stated that in the case of trawler infiltration after the implementation of Operation Market Time just one out of every twenty trawlers were able to reach the South Vietnamese coast undetected.[12]
This number is certainly encouraging, yet it does not fully reflect all possible cases in which craft reached shore unbeknownst to American intelligence. Similar to the high body count numbers in accordance with the doctrine of attrition, scholars fear that boarding and inspection numbers were also inflated by soldiers and commanders.[13] Even considering all of these factors, Market Time had an undeniable effect on infiltration into South Vietnam. Throughout the course of 1966 alone allied forces detected 807,946 watercraft, visually inspected 223,482 of them, and boarded 181,482. Forces also engaged in a total of 482 firefights, killed 161 VC soldiers, and captured 177 while experiencing 21 friendly deaths and 97 other casualties.[14]
A study by the BDM Corporation concluded that at the very least the operation forced the VC to drastically alter its logistic operations. The company also stated that at the beginning of 1966 almost 75% of enemy resupply came from the sea along the South Vietnamese coast. By early 1967 this number had been reduced to just 10%.[15]
Notes
[edit]Citations
[edit]References used
[edit]- Cutler, Thomas J. (1988). Brown Water, Black Berets. Annapolis, MD: United States Naval Institute. ISBN 0-87021-011-4. OCLC 17299589.
- Kelley, Michael P. (2002). Where We Were in Vietnam. Hellgate Press, Central Point, Oregon. ISBN 978-1-55571-625-7.
- Larzelere, Alex (1997). The Coast Guard at War, Vietnam, 1965–1975. Naval Institute Press, Annapolis, Maryland. ISBN 978-1-55750-529-3.
- Noble, Dennis L. (1984). "Cutters and Sampans". Proceedings. 110 (6). United States Naval Institute: 46–53.
- Olson, James S. (2008). In Country: The Illustrated Encyclopedia of the Vietnam War. New York: Metro Books. ISBN 978-1-4351-1184-4. OCLC 317495523.
- Schreadley, R. L. (1992). From the Rivers to the Sea: The U.S. Navy in Vietnam. Annapolis, MD: Naval Institute Press. ISBN 0-87021-772-0. OCLC 23902015.
- Scotti, Paul C. (2000). Coast Guard Action in Vietnam: Stories of Those Who Served. Hellgate Press, Central Point, Oregon. ISBN 978-1-55571-528-1.
- Summers Jr., Harry G. (1995). Historical Atlas of the Vietnam War. Houghton Mifflin Co., New York, New York. ISBN 978-0-395-72223-7.
Other references not cited in article
[edit]- Steffes, James ENC Retired, "Swift Boat Down, The Real Story of the Sinking of PCF-19", Xlibris, 2006, ISBN 1-59926-612-1 [self-published source]
- Steffes, James ENC Retired, "Operation Market Time, The Early Years 1965-66", Xlibris, 2009, ISBN 978-1-4415-9049-7 [self-published source]
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Operation Market Time
View on GrokipediaStrategic Context
Pre-Operation Seaborne Threats
North Vietnamese forces and the Viet Cong relied heavily on maritime infiltration routes to supply insurgents in South Vietnam prior to 1965, leveraging the country's 1,200-mile coastline for landings in isolated bays and beaches that bypassed heavily patrolled land corridors. These operations involved small coastal junks and larger steel-hulled trawlers departing from northern ports like Haiphong or Quang Khe, navigating southward while hugging the shore to evade radar detection and open-water patrols. Cargo typically consisted of arms, ammunition, rice, medical supplies, and personnel, providing an economical alternative to overland trails vulnerable to air interdiction.[5][2] The scale of these threats grew amid escalating ground warfare, with sea routes enabling sustained resupply to coastal provinces where Viet Cong units conducted ambushes and sabotage. South Vietnam's navy, equipped with fewer than 100 patrol vessels including outdated U.S.-loaned ships, conducted sporadic intercepts but lacked the assets for continuous coverage, allowing infiltrators to exploit gaps in surveillance. Intelligence assessments noted the sporadic yet persistent nature of shipments, estimating that maritime deliveries supplemented up to 20-30% of Viet Cong logistics in southern regions before systematic countermeasures.[6][2] A pivotal demonstration of the vulnerability occurred on February 16, 1965, in Vung Ro Bay, Khanh Hoa Province, where U.S. and South Vietnamese forces intercepted a 100-ton North Vietnamese trawler unloading munitions after it ran aground while evading pursuit. The vessel carried approximately 100 tons of war materiel, including 3,750 rifles, 130 machine guns, 947 anti-personnel mines, and over 1 million rounds of ammunition, confirming Hanoi's direct naval role in arming southern insurgents. This incident highlighted the inadequacies of prior ad hoc patrols and the increasing sophistication of enemy tactics, such as using disguised fishing craft for covert beachheads.[7][8][9]Escalation in Vietnam War Logistics
Following the Gulf of Tonkin incidents on August 2 and 4, 1964, which prompted the U.S. Congress to pass the Gulf of Tonkin Resolution on August 7 authorizing expanded military involvement, North Vietnam accelerated its infiltration of personnel and materiel into South Vietnam to bolster communist forces against the anticipated U.S. buildup. U.S. troop levels in South Vietnam stood at approximately 23,000 in January 1965, reflecting a shift from advisory roles to combat operations amid intensifying Viet Cong insurgency, which had grown to an estimated 80,000–100,000 fighters by late 1964.[10] [11] North Vietnam responded by directing the People's Army of Vietnam (PAVN) in November 1964 to infiltrate organized units southward for joint operations with the Viet Cong, necessitating a surge in logistical support to sustain expanded combat capabilities. Between 1964 and 1969, North Vietnam's overall infiltration system delivered over 500,000 troops alongside substantial munitions to South Vietnam, with sea routes supplementing the primary Ho Chi Minh Trail land network, particularly for resupplying southern and coastal areas where overland paths were longer and more vulnerable to interdiction.[12] The Viet Cong's requirements for weapons, ammunition, and foodstuffs escalated as U.S. air and ground operations disrupted local foraging and captured caches, forcing reliance on external pipelines that averaged 5–12 tons per day through key passes during the 1964–1965 dry season.[13] Seaborne infiltration, conducted via disguised fishing junks and increasingly steel-hulled trawlers, emerged as a critical vector for evading detection along South Vietnam's 1,200-mile coastline, which lacked systematic surveillance prior to 1965.[2] These operations transported men and supplies directly from North Vietnamese ports to remote beaches, with intelligence indicating viable, unchecked volumes into regions beyond the Mekong Delta focus, though precise pre-1965 quantities remained difficult to quantify due to limited monitoring.[14] By early 1965, the adoption of larger trawlers capable of carrying 100 tons or more signaled a tactical escalation in payload capacity, as evidenced by subsequent interceptions revealing arms and munitions intended for Viet Cong units.[7] This maritime approach exploited the absence of dedicated coastal patrols, allowing North Vietnam to maintain logistical momentum amid U.S. escalation without proportional disruption to sea-based flows.[1]Establishment
Vung Ro Bay Incident
On February 16, 1965, U.S. Army Lieutenant James S. Bowers, piloting a helicopter during a medical evacuation mission near Vung Ro Bay in central South Vietnam, observed a camouflaged steel-hulled trawler unloading cargo onto a remote beach.[8][2] The 130-foot North Vietnamese vessel, with a 100-ton capacity, was transporting supplies destined for Viet Cong insurgents.[7][2] Alerted by the sighting, U.S. naval aviation conducted airstrikes that capsized the trawler, while ground forces, including South Vietnamese marines advised by U.S. Navy Lieutenant Harvey P. Rodgers, assaulted the beach area.[8][2] Divers later confirmed the wreck as a North Vietnamese infiltrator vessel.[2] Searches of the site uncovered approximately 100 tons of arms, ammunition, explosives, rice, and medical supplies, along with North Vietnamese charts and military documents indicating coordination with the People's Army of Vietnam's 338th Division.[7][8] The incident demonstrated the feasibility of large-scale seaborne resupply evading prior coastal defenses, revealing systemic infiltration routes and prompting U.S. military leaders to establish Operation Market Time on March 24, 1965, to blockade South Vietnam's 1,200-mile coastline.[2][7]Objectives and Initial Deployment
The primary objective of Operation Market Time was to interdict seaborne infiltration of personnel, arms, ammunition, and supplies from North Vietnam into South Vietnam by establishing surveillance barriers along the coastline.[2] This aimed to disrupt Viet Cong and People's Army of Vietnam logistics that relied on coastal routes to evade land-based interdiction.[15] Secondary goals included preventing transshipment of contraband between coastal points within South Vietnam and detecting, inspecting, and boarding suspicious vessels to enforce a de facto blockade.[2][1] Operation Market Time commenced on March 11, 1965, following planning from March 3 to 10 and authorization by President Lyndon B. Johnson on March 15, as Task Force 115 under the Coastal Surveillance Force.[2][15] Initial deployment featured a tiered barrier system covering South Vietnam's 1,200-mile coastline, divided into eight patrol areas (later nine), with five coastal surveillance centers at Da Nang, Qui Nhon, Nha Trang, Vung Tau, and An Thoi.[2] The outer barrier, extending 40 nautical miles offshore, relied on patrol aircraft such as P-2 Neptune, P-3 Orion, and P-5 Marlin for detection and reporting of vessels.[2][1] Surface forces formed inner and middle barriers: the middle utilized U.S. Coast Guard cutters for intercepting larger cargo ships, while the inner barrier (3-12 nautical miles offshore) employed U.S. Navy Patrol Craft, Fast (PCF Swift boats) and South Vietnamese Navy junk forces for close-in patrols and boardings.[1][15] Initially, 15 U.S. Navy ships—including destroyers and minesweepers—provided barrier coverage, averaging sustained presence for the first three months, supplemented by radar picket escorts like destroyer escorts (DERs) for enhanced detection.[2] By mid-1965, reinforcements included 17 Coast Guard 82-foot patrol boats (WPBs) arriving in July and Swift boats phasing in from April, with eight operational by year's end.[2] Task Force 115 comprised three squadrons: two U.S. Navy and one U.S. Coast Guard, integrating riverine assets like patrol boats for flexible response.[15]Operational Framework
Command Structure and Coordination
Operation Market Time was directed by Task Force 115 (TF 115), the U.S. Coastal Surveillance Force, established on 24 March 1965 initially as Task Force 71 under Commander Seventh Fleet to interdict coastal infiltration.[16] Command authority transferred shortly thereafter to the Naval Advisory Group, subordinate to Military Assistance Command, Vietnam (MACV), enabling closer integration with ground operations.[2] By 31 July 1965, operational control shifted to Commander U.S. Naval Forces Vietnam (COMNAVFORV), with TF 115 headquartered in Saigon to oversee unified sea, air, and supporting land elements.[4] TF 115 coordinated multinational assets, including U.S. Navy destroyer escorts, patrol gunboats (Swift boats), and P-5B Marlin flying boats for surveillance; U.S. Coast Guard high-endurance cutters and patrol boats operating under Navy direction; and Republic of Vietnam Navy (RVNN) coastal patrol vessels, which numbered over 100 by mid-1965.[2][17] This structure addressed prior RVNN command-and-control deficiencies by centralizing decision-making, with TF 115 directing three concentric patrol zones along South Vietnam's 1,200-mile coastline: an inner junk barrier, a middle swift boat/Coast Guard patrol line, and an outer destroyer/aircraft screen extending 100 miles offshore.[2][16] Coordination relied on real-time intelligence sharing via naval communication networks, including radar picket ships and airborne patrols from Patrol Squadron 22 (VP-22) and others, which vectored surface units to suspected targets; this multi-service approach, incorporating Royal Australian Navy contributions from 1967, minimized overlaps and maximized coverage despite logistical strains from divided zones.[18][19] RVNN integration improved over time through joint training and advisory oversight, though early challenges persisted due to language barriers and varying vessel capabilities, prompting U.S. forces to assume primary interdiction roles initially.[2]Surveillance and Patrol Assets
Operation Market Time utilized a coordinated array of surface vessels and aircraft to maintain continuous surveillance and patrol over South Vietnam's extensive coastline, spanning approximately 1,200 nautical miles from the Demilitarized Zone to the Gulf of Thailand.[2] These assets operated under Task Force 115 (later Coastal Surveillance Force), integrating U.S. Navy ships, U.S. Coast Guard cutters, and Republic of Vietnam Navy vessels with air support for radar, visual, and electronic detection of infiltrators.[20] Surface patrol assets emphasized speed, endurance, and radar capability. U.S. Navy Patrol Craft, Fast (PCF), or "Swift boats," 50-foot aluminum-hulled vessels powered by twin diesel engines achieving 28 knots, were armed with twin .50-caliber machine guns forward and an 81mm mortar aft for rapid interdiction of small craft.[15] These boats, organized into coastal divisions, conducted close-in patrols and boarding operations, with dozens deployed by mid-1965 to cover high-threat sectors.[20] Complementing them were radar-equipped destroyer escorts (DERs) for offshore radar picket duties and minesweepers (MSCs) for shallow-water surveillance, providing extended radar coverage linked to shore-based control centers.[8] U.S. Coast Guard high-endurance cutters (WHECs), primarily 311-foot Owasco-class vessels like USCGC Owasco (WHEC-39), offered long-range patrol endurance of up to 14,000 miles, armed with a 5-inch/38-caliber gun, sonar, and helicopter decks for vertical replenishment and observation; seven such cutters formed Squadron Three, rotating through deployments starting in 1965 for sustained barrier patrols.[3][21] ![SP-5B VP-40 on Vietnam patrol 1965.jpg][center] Air surveillance assets provided broad-area coverage and precise targeting data. Patrol Squadron (VP) aircraft, including SP-5B Marlin flying boats operated by VP-40 from Cam Ranh Bay, conducted magnetic anomaly detection (MAD) sweeps and visual reconnaissance over coastal waters from 1965 until their phase-out in 1966-1967, with the last operational SP-5B flight occurring on July 6, 1967.[22][23] Transitioning to land-based P-3A/B Orion four-engine turboprops, VP squadrons extended endurance to over 10 hours per sortie, equipped with radar, infrared sensors, and sonobuoys for detecting steel-hulled trawlers and coordinating intercepts.[2][8] Lighter fixed-wing aircraft such as OV-10 Broncos and initially A-1 Skyraiders, supplemented by UH-1 helicopters from Army and Navy units, performed low-level visual identification of suspect vessels, relaying coordinates to surface forces for rapid response.[8] This layered approach ensured 24-hour coverage, with aircraft sorties peaking at hundreds per month by 1966, directly enabling the interdiction of enemy resupply efforts.[2]Key Tactics and Engagements
Operation Market Time employed a layered coastal patrol system consisting of three concentric barriers to interdict seaborne infiltration along South Vietnam's 1,200-mile coastline. The outer barrier, extending into international waters, utilized maritime patrol aircraft such as P-3 Orions and SP-5B Marlin flying boats for long-range surveillance, supplemented by radar-equipped destroyer escorts (DERs) and minesweepers to detect steel-hulled trawlers approaching from North Vietnam or Cambodia.[8][2] The middle barrier, within 40 nautical miles offshore, involved U.S. Navy destroyers, Coast Guard high-endurance cutters (WHECs) equipped with 5-inch guns, and Patrol Craft Fast (PCFs or "Swift boats") for rapid response and boarding.[8] The inner barrier focused on shallow waters near the coast and river mouths, patrolled by PCFs, 82-foot Coast Guard patrol boats (WPBs), and South Vietnamese navy junks to inspect fishing vessels and prevent offloading.[2] Surveillance was coordinated through the Market Time Air Surveillance Center (MASC), which integrated airborne spotters, helicopter relays, and ground radar stations to vector surface units toward suspects, enabling near-real-time tracking.[8] Tactics emphasized visit, board, search (VBS) procedures under rules of engagement that permitted halting, inspecting, and boarding any non-warship within the patrol zones, with escalation to fire only if vessels resisted or posed an imminent threat.[2] Initial overt surveillance tracked infiltrators but often aborted in international waters to avoid escalation; by 1970, shifts to covert tracking lured trawlers into South Vietnamese waters for destruction.[2] The "cloud concept," implemented in 1971, concentrated mixed task units—typically one patrol gunboat with four PCFs or WPBs—in intelligence-identified high-threat sectors for rapid encirclement and search of suspect junks or sampans.[2] These methods inspected thousands of vessels, with U.S. forces boarding about 15% of junks, though contraband seizures were limited due to the volume of legitimate fishing traffic.[2] Key engagements highlighted the operation's focus on steel-hulled trawlers used for large-scale resupply. The most significant occurred during the Tet Offensive on the night of February 29, 1968, when North Vietnam coordinated four simultaneous infiltration attempts to bolster forces in the south. Near the 17th parallel, USS Minnetonka intercepted a trawler that reversed course northward without destruction.[8] Northeast of Nha Trang, a trawler was forced aground and destroyed, yielding salvage of seven mortar tubes, 745 rounds, 70 AK-47 rifles, 39 RPG-2 launchers, and 28 ammunition cases.[8] South of Da Nang, USS Androscoggin, WPB Point Welcome, Point Grey, and helicopter gunships engaged and destroyed a beached trawler.[8] Off the Ca Mau Peninsula, USS Winona, WPBs Point Grace, Point Marone, Point Hudson, and PCFs sank another.[8] Overall, this multi-trawler push saw three of four vessels destroyed, demonstrating coordinated allied response but also enemy determination.[2] Later, in November 1970, covert surveillance enabled the destruction of one trawler in South Vietnamese waters, and on April 24, 1972, another (SL-4) was sunk in the Gulf of Thailand.[2] The Coast Guard's first combat action came on September 19, 1965, involving WPBs in fire support and interdiction.[24] Across the operation, 12 trawlers were detected in the first phase (1965–1968), with eight destroyed or partially so.[2]Effectiveness and Impact
Interdiction Achievements
Operation Market Time achieved substantial success in curtailing North Vietnamese and Viet Cong seaborne infiltration into South Vietnam, reducing the proportion of enemy logistics reliant on maritime routes from an estimated 75% in early 1966 to less than 10% by the end of that year.[15] This shift compelled the enemy to depend more heavily on overland trails such as the Ho Chi Minh Trail, thereby straining their supply capacity and contributing to broader strategic disruptions.[15] The operation's effectiveness stemmed from persistent surveillance, rapid response capabilities, and coordinated interdictions that intercepted steel-hulled trawlers and smaller craft attempting to deliver arms, ammunition, and personnel.[2] U.S. Coast Guard units, particularly Squadrons One and Three, played a pivotal role in close-in patrols, boarding 237,490 vessels and inspecting 333,527 overall during their deployments from 1965 to 1972.[25] These efforts yielded 1,811 enemy vessels damaged or destroyed through direct action and naval gunfire support, alongside 1,827 enemy personnel killed or wounded and 10,286 detained.[25] Allied forces, including U.S. Navy and South Vietnamese elements, inspected hundreds of thousands of additional commercial and private vessels between May 1967 and January 1972, engaging in 482 firefights and killing or capturing over 300 smugglers while seizing Soviet- and Chinese-manufactured arms caches.[26] High-value targets like infiltration trawlers faced near-total interdiction rates; of 12 attempts detected from March 1965 to March 1968, all were intercepted with total or partial destruction, and among 38 attempts from August 1969 to April 1972, only two succeeded in infiltration.[2] Notable actions included the destruction of three trawlers on February 29, 1968—the largest naval surface engagement of the war—yielding recovered medical supplies, and the sinking of others in 1970–1972 with munitions such as 120mm mortars and 12.7mm ammunition.[2][15] By August 1968, these measures had effectively eliminated large-scale smuggling by sea, validating the operation as a deterrent despite challenges in quantifying every prevented shipment.[2]Strategic Disruption of Enemy Supply Lines
Operation Market Time significantly curtailed North Vietnamese and Viet Cong seaborne infiltration routes along the South Vietnamese coast, compelling a strategic shift to overland supply lines. Prior to the operation's full implementation in March 1965, intelligence assessments indicated that up to 90 percent of arms and supplies reaching Viet Cong forces arrived via maritime routes from North Vietnam.[8] By early 1966, approximately three-quarters of enemy resupply efforts relied on sea infiltration, but intensified patrols reduced successful deliveries dramatically.[15] This interdiction effectively neutralized large-scale boat operations, as radar picket ships, swift boats, and Coast Guard cutters intercepted steel-hulled trawlers and sampans attempting to offload munitions near key coastal points.[16] The operation's success forced the North Vietnamese to redirect logistics through inland trails, such as the Ho Chi Minh Trail via Laos and Cambodia, which proved more vulnerable to allied air interdiction and extended transit times.[27] By the end of 1966, seaborne resupply had been virtually halted, with weekly intelligence reports documenting a sharp decline in detected enemy coastal activity from North Vietnamese ports.[15] This disruption not only strained enemy command's logistical planning but also amplified the impact of complementary operations like Rolling Thunder bombings on land routes, as sea alternatives diminished. Sustained surveillance from patrol aircraft and destroyers ensured that attempted infiltrations, such as those by trawlers in later years, faced near-total interception rates, with only minimal successes recorded by 1971.[28] Overall, Market Time's coastal barrier transformed enemy sustainment strategies, increasing dependency on protracted overland convoys that incurred higher losses from attrition, ambushes, and aerial strikes, thereby contributing to broader attrition of insurgent capabilities in South Vietnam.[2] While not eliminating all infiltration, the operation's emphasis on persistent presence and rapid response degraded the efficiency of seaborne logistics, validating the causal link between maritime denial and forced reliance on costlier alternatives.[16]