Period 2

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MAC-V-SOG Command History Annex B:
(1971-1972) Volume I, 
The Last Secret of the Vietnam War
by Charles F. Reske

    [Webmaster note: This web page includes excerpts from the second book in a series of three.]

3. Maritime Studies Group, MACSO-37 (Appendix 11). The Maritime Studies Group was responsible for covert maritime operations conducted by the Vietnamese Coastal Security Service (CSS). The capability to carry out missions against North Vietnam was maintained through extensive training at Da Nang and by conducting operational missions against selected targets in South Vietnam. ---SENTENCE DELETED-- CSS had progressed to such a point by July 71 that they assumed all responsibility from the US for planning and carrying out missions. ---SECTI0N DELETED --


Nightly training patrols with the PTF's were conducted from Da Nang north to the DMZ and south to Cu Lao Re Island, located to the east of Chu Lai. The PTP's departed Da Nang at 18:00 H on a twelve hour patrol. Training emphasized navigation and tactics. Suspected enemy craft were stopped and searched, if within the twelve mile limit. This training program started on 15 Dec 70 and is intended to continue indefinitely.


A mission using four PTF's in the Hon Nieu Island area was run on 19 and 20 Feb. Three large targets were observed west southwest of Hon Nieu Island.

One was a 380 foot freighter in the Hung Chi 151, 152, or 153 class. It had a yellow star and stripe on its stack and was determined to be of Chinese registry. The presence of this type of ship at this location was confirmed by aerial photography on 16 Feb. 

The other two targets were a 300 foot tanker and a 200 foot freighter. While photographing these vessels, an enemy 60 foot patrol craft approached from the south and fired 12.7mm guns at the PTF's. The enemy craft was engaged and strafed by 40mm and 50 caliber fire and was sunk at 2240 hours on 19 Feb. One hour later, one probable Swatow class enemy craft and one possible Swatow or Shanghai class vessel were engaged, resulting in both enemy boats heavily damaged. The PTF force continued south, passing between Hon Gio Island and the North Vietnam coast, when they ware ambushed by one probable P-4 craft and one probable Shanghai II class vessels. The P-R was heavily damaged and evaded, while the second craft approached from Hon Gio Island and engaged one of the PTF's, resulting in one friendly KIA and the enemy sunk.

Four PTF's have been modified to fire captured 122mm rockets at the enemy. Two rocker tubes are mounted on each side of the PTP's. If all four PTF's are employed, they possess the capability of firing sixteen 122mm rockets simultaneously against a given target at a standoff range of 11,000 meters.


At total of six DODGE MARK missions were planned and five were conducted during this period.  On 29 Mar, DODGE MARK 12 was conducted and made contact with one enemy who tried to escape and was killed.  One hand weapon and a small quantity of documents was captured.

DODGE MARK 17 was conducted in the DMZ on 20 Apr.  No contact was established, however, the PTF's conducted shore bombardment for 15 minutes. 


Typhoon Hester caused considerable damage to MACSOG maritime forces. Of the five PTF's and three PCF's at Da Nang, two PTF's and 1 PCF were sunk at the height of the storm.  All boat crews were aboard the craft with the engines running and mooring lines tended. They were successfully riding out the storm when an adjacent pier parted its pilings, and was driven into the three boats that sunk.  Alert and timely actions on the part of the Coastal Security Service and US Naval Advisory personnel prevent serious injury and damage. Salvage operations were started immediately.


A NEWPORT CASINO operation with the mission of interdicting enemy shipping off the North Vietnamese coast in the vicinity of Quang Khe was conducted. Three PTF's participated in this operation, departing Da Nang at 1800H on the evening of the 10th and proceeding north to a position just north of Hon Gio Island. The PTF's then turned southwest and commenced their area patrol. On 11 Feb, at 2330H, radar contact was made and visual contact was made twenty minutes later with two junks. Each had two masts and a single engine. A shot was fired across the bow of the first junk at 0305H. The second boat attempted to evade and was taken under fire by one of the PTF; causing one secondary explosion and setting the junk on fire. The craft entered shallow water and beached itself. The second junk was also taken under fire after it attempted to evade. The vessel soon ceased its attempts to evade, allowing one PTF to come alongside. A search party boarded the junk, captured six crew members and approximately one kilogram of documents, and placed demolition charges below deck. The junk was subsequently destroyed. Radar contact was established with another target at 0340H, while the second junk was being searched. One PTF took this craft, a TL-15 coastal cargo vessel, under fire after it attempted to evade. The craft was 87 feet long and had a displacement of approximately 100 tons. The ship sustained three large secondary explosions and began to burn. After the fire subsided, one PTF came alongside and placed a search party aboard. No live crew members were found, but several charred bodies were observed. Cargo boxes were observed on deck covered with tarps. The search party placed demolitions and subsequently destroyed the ship. Later two injured crew members were recovered from the water near the craft.

At 0500H on the 11th, the PTF personnel observed a SL-4 type trawler showing lights. The PTF crew observed Chinese characters and a North Vietnamese flag painted on its stack. Gun mounts were observed as the PTF made a second pass and fired a warning shot across the trawler's bow. The trawler attempted to evade and was taken under fire by all three PTFs. The trawler returned fire and was observed to be communicating with a shore station with signal lights. The trawler entered shallow water and one PTF continued the engagement. However, when the trawler entered the south of the Cue Gaing River the PTF was forced to break off the engagement. No further targets were observed, and the PTF's returned to Da Nang arriving at 1045H on the 11th. The prisoners were placed in isolation and interrogated by ARVN intelligence personnel.


One of the most productive branches in the SOG organization was MACSOG-31, the Maritime Studies Branch. Possessed of an action arm known as the Maritime Studies Group (MACSOG-37), which operated under the cover name Naval Advisory Detachment, it had an excellent operational  record from inception in 1964 to disestablishment in 1972. 

The majority of naval operations against North Vietnam in 1964 were DeSoto patrols, which consisted of destroyers and aircraft operating in the Tonkin Gulf disassociated from all OPLAN 34A MAROPS . 

In the event of hostile attack, the patrol ships and aircraft were directed to fire upon the hostile attacker with the objective of insuring destruction. Ships were to pursue the enemy to the recognized three mile territorial limit, while aircraft were authorized hot pursuit inside territorial waters against surface vessels and into hostile airspace, (which included NVN, Hainan Island, and Mainland China) against attacking aircraft when necessary to achieve destruction of identified attacking forces.

Originally, MAROPS had been designed to inflict psychological damage on the North Vietnamese by demonstrating the NAD/CSS ability to strike targets well above the 17th parallel. Destructive results and military utility were considered secondary, though U.S. aircraft were later added to the equation for cover operations above the 19th parallel.

Early OPLAN 34A operations were so successful that at one point the U.S. government considered going public with a handful of tangible victories in an effort to bolster the South Vietnamese and drum up popular American support for the growing war effort.

Typical 1964-1972 MAROPS---fine tuning, as such, of more conventional  naval activities---consisted of shore bombardment  utilizing Russian-made 122mm rockets mounted aboard PTF's (the so-called Nasty Class boats), junk captures, the kidnapping and disruption of the Viet Cong Infrastructure (VCI) in coordination with Provincial Reconnaissance Units below the 17th parallel, and Sea Commando Team demolition sorties against coastal radar, highways, and bridges. While SOG 31/37 possessed the capability for inland operations, most of their in shore coastal operations were of the shallow penetration variety,

Among the broad categories addressed in MACSOG-31 spot reports were such items as North Vietnamese paramilitary activities, air defense, conscription, coastal sea transportation, population controls, the identification of dissident groups, effects of the war on the NVN economy, and the governmental and popular reaction to friendly psywar activities.

SOG's concern over paramilitary activities extended beyond NVN support for the Viet Cong. One of the earliest issues addressed by the Maritime Studies Branch concerned the NVN effort to recruit and train Meo tribesmen. Since South Vietnam's relations with its own Montagnards lay somewhere between indifference and genocide, any attempt by NVN to win over a people born and bred to environmental hardship had to be viewed as a viable threat. SOG's experience with the capabilities of South Vietnam's tribal peoples convinced them that this was a legitimate consideration 

In the area of psychological warfare, SOG's efforts revolved around gift kits, pre-set radios, and actions against North Vietnam's fishing industry. Despite great effort, the psywar operations garnered few positive results and constituted one of the least successful aspects of the covert maritime war.


(S) Maritime Studies Branch, MACSOG-31, continued to exercise staff supervision and coordination for MACSOG covert maritime operations (MAROPS). MAROPS were conducted by the Martime Studies Group, MACSOG-37, under the cover name of Naval Advisory Detachment (NAD), Da Dang, in conjunction with the Coastal Security Service (CSS) of the Vietnamese  Strategic Technical Directorate (SPD).

MACSOG-31 was disestablished on assumption of advisory status, 30 Apr 72. 

(TS) The type and tempo of MAROPS in 1971 and 1972 wars similar to those of those of 1970  with the exception of operations north of the 17th parallel in Feb and Dec- 71 when the restrictions on northern missions were temporarily suspended. MAROPS emanating from NAD continued in the Military Region I (MR I) area, with the primary target shifting from interdiction of NVA movement to disruption of the VC infrastructure in coordination with Provincial Reconnaissance Units (PRU).

(S) The seven Patrol Boats, Fast (PTFs) and related equipment were returned to US control.


(TS) In Jan 71, at the direction of CINCPAC, Maritime Studies Branch developed five operation plans to support covert maritime operations against North Vietnam.

    1. MACSOG  OPLAN 5-70 (CLAY DRAGON): Utilized PTFs to transport Sea Commando Teams (SCTs) to designated targets along the North Vietnamese coast. The SCTs were to conduct amphibious raids against transshipment points to destroy/disrupt normal logistic flow.

    2. MACSOG OPLAN 2-'71 (BOSTON ANTIQUE): Utilized PTF's to intercept and destroy infiltration trawlers that had been designated a threat by CINPAC.

    3. MACSOG OPLAN 3-71 (HAI CANG TUDO-2): Utilized PTF's to conduct shore bombardment of designated transshipment areas along the coast of North Vietnam.

    4. MACSOG OPLAN 4-71 (GLYNN REEF): Utilized PTF's to destroy/disrupt the North Vietnamese fishing industry along the coast of North Vietnam.

    5. MACSOG OPLAN 5-71 (HAI CANG TUDO-1): Utilized PTPs for interdiction of North Vietnamese coastal shipping along the coast of North Vietnam.

(TS) In Feb 71, a JCS message authorized the execution of MACSOG OPLAN 5-71. The following two missions were conducted: 

    1. During the night of 10 to 11 Feb, three PTFs patrolling off  QUANG KHE, North Vietnam sank a motorized junk, an 8·ft TL-15 coastal cargo vessel, and damaged another motorized junk and an SL-4 trawler.

    2.  During the night of 10 to 20 Feb four PTPs patrolling from VINH to QUANG  KHE, North Vietnam, sank a 60 ft patrol craft and a 130 ft SHANG HAI II, and damaged another SHANG HAI II and two SO-1 craft.

(TS) In mid-Feb 71, MACSOG-31 submitted to NAD a concept for mounting communist-made 122mm rockets on the PTFs. NAD developed the idea and installed the launchers by 1 Mar 71. Two salvos of four rounds could be fired in a 15 minute period at a standoff range of 11,000 meters. The addition of the launchers significantly increased the PTP coastal bombardment potential. MACSOG OPLAN 3-1 was modified to include the new capability.

(TS) During Dec 71, JCS authorized the execution of MACSOG 3-71. Two missions were launched from Da Nang:

    1. During the night of 26-27 Dec four PTFs were ordered to  conduct a 122mm  rocket attack on QUANG KHE. The mission was aborted north of the 17th parallel due to extremely heavy sea conditions.

    2.  During the night of 27-28 Dec, three PTF's were ordered to conduct a 122mm rocket attack on QUANG KHE and DONG HOI. While approaching the target the command PTF suffering an engineering casualty and had to abort.  The other two PTF's attempted to close the target but were unable to do so due to the presence of enemy craft in the firing area.


(S) Continuous refresher training at NAD emphasized gunnery and unit tactics.  CSS also began a program of officer billet rotation to broaden the level of experience.  A radar/electronics course was conducted in Apr 71, and two Napier Deltic engine maintenance courses were conducted September through December at the Ship Repair Facility, Subic Bay, Republic of the Philippines.


(C) SCT training was exercised through DODGE MARK operations.  These were supplemented by classes in ambush tactics, small arms firing, map and compass reading, rubber boat operations, and physical fitness.  A training class in Oct-Nov 71 prepared 15 new Sea Commandos for integration into the unit and brought the total number of SCTs to five.


(S) With the exception of overhaul of Napier Deltic engines, complete PTF repair and maintenance was conducted in Da Nang.  The NAD mini-drydock was returned to the Ship Repair Facility, Subic Bay, and NAD's PTF lift requirement was assigned to the LSB, Da Nang.