Operation Coronado IX

Operation Coronado IX was a riverine military operation conducted by the Mobile Riverine Force of the United States and elements of the Army of the Republic of Vietnam from November 1967 to January 1968 in an attempt to dismantle communist strongholds in the Mekong Delta. In the middle of November, clashes resulted in the capture of communist supplies and hideouts. During this period, the communists lost 178 men but killed only 26. For the next few weeks there was little contact, although some abandoned communist bunkers were destroyed and supplied captured. On 4 December, large engagement occurred when a communist battalion encountered a battalion of South Vietnamese marines. There were 266 Vietcong killed, mostly by South Vietnamese marines. The South Vietnamese Marines lost 40 killed, while the Americans suffered 9 dead. Over the next month and the Christmas period, there was only sproadic skirmishes, but at the start of the new year, there were some medium size battles in which the Americans killed a few dozen communists. After this there was little contact.

First phase
It began with the movement of the Mobile Riverine Base from its late October anchorage off Vung Tau to an anchorage in the My Tho River near Dong Tam. The series of actions in the operation was primarily conducted north of the My Tho River and directed against communist bases in Dinh Tuong Province.

The Mobile Riverine Force arrived off Dong Tam on 1 November 1967 and during early November concentrated on equipment maintenance and preparations for coming operations. The 3d Battalion, 60th US Infantry Regiment, disembarked and assumed the defense mission for Dong Tam Base. The battalion's waterborne replacement was the 3d Battalion, 47th US Infantry Regiment, which began tactical operations in the southeastern part of Giao Duc District in western Dinh Tuong Province at 1500 on 2 November. During the nine-hour operation, the battalion destroyed 141 communist bunkers and evacuated 500 kg pounds of rice and an assortment of Vietcong engineering and medical materials from a cache. The evacuated materials were delivered to Dinh Tuong Province Headquarters for distribution within South Vietnamese government programs.

On 5 and 6 November, the two Americans operated in Cam Son Secret Zone. Barge-mounted artillery supported infantry from a position on the north shore of the My Tho River. During this operation the Mobile Riverine Force destroyed 34 bunkers, captured 360 kg of rice and 55 kg of salt, and killed five communists.

The Americans were joined by the 5th Battalion of the Republic of Vietnam Marine Corps at a shore camp near My Tho on 6 November, yielding a third anti-communist battalion. The South Vietnamese marine battalio had four rifle companies and a heavy weapons company, a strength equal to that of the two embarked American battalions. The Americans said that the South Vietnamese marines "brought a special esprit to the Mobile Riverine Force and fought extremely well throughout" the operation, under the leadership of a Major Nam, who joined the Americans in the planning of the operation. The US Navy assault craft, army artillery, and Air Force planes supported three infantry battalions.

After a short time used for training and maintenance, the Mobile Riverine Force and the South Vietnamese Marines resumed Coronado IX on 9 November, targeting the 263d and 514th Viet Cong Battalions in the Cam Son area. While the US 3d Battalion, 47th Infantry, and the 5th Republic of Vietnam Marine Battalion made beach assaults early on 9 November, the 4th Battalion, 47th Infantry, which had been moved by ATC to the Dong Tam airstrip, and then in a series of helicopter lifts entered the area of operations to become the fourth anti-communist battalion in action. All landings of anti-communist forces were unopposed and they saw few Vietcong.

On the second day the search for communist forces shifted to the east; troops were moved by boat and helicopter into the Ban Long and the Ap Bac base areas. Only the South Vietnamese Marine battalion, which remained in its original location, saw action, killing seven communists.

On 14 November, to increase security for Highway 4 and the Dong Tam Base area, a new operation began, with support from American artillery at Dong Tam. While the 3d Battalion, 47th Infantry, remained at the Mobile Riverine Base for maintenance, the other battalions were transported by boat and helicopter to the north along the Kinh Xang Canal east of Dong Tam Base. The 5th Republic of Vietnam Marine Battalion and the 4th Battalion, 47th US Infantry, destroyed 63 bunkers and seized 900 kg of rice and 90 kg of salt. This operation continued through the night; platoon-sized ambush patrols were sent out along Highway 4 north of Dong Tam but could not intercept many communists.

On 16 November the Mobile Riverine Force began operations with the 3d Brigade, 9th US Division, and elements of both the 7th Division and 9th ARVN Divisions along the border of Kien Phong and Dinh Tuong Provinces. The anti-communists targeted the 502d Local Force and 267th Main Force Vietcong Battalions, which IV Corps and II Field Force intelligence predicted were in Base Area 470. Troops of the 3d Brigade were landed by helicopter in the northern part of the area along with the 3d Battalion, 47th Infantry, which was initially under the control of the 3d Brigade. Since Base Area 470 lacked firm ground needed for artillery fire support bases, and artillery positioned along Highway 4 could not reach the area, experimental artillery firing platforms were used.

One platform accommodated an M102, 105-mm. artillery piece, ammunition, and space for the crews to operate. The legs of the platform were adjustable to various heights and a large metal "foot" on the bottom of each leg, provided support in the muddy rice paddies. A CH-47 helicopter carried the platform, artillery piece, ammunition, and crew to their operational locations in four lifts. One battery of 105-mm. artillery was used throughout the operation. On the second night of the 3d Brigade's operations, 17 November, the Vietcong attacked one of the brigade's fire support bases. The attack was repulsed several hours before the Mobile Riverine Force entered the operational area off the My Tho River on the Rach Ruong Canal. To allow the Mobile Riverine Force to enter the operational area, IV Corps South Vietnamese engineers, who were accompanying the assault forces early on the morning of 18 November, had to remove the center span of the bridge on the Rach Ruong Canal.

Before the bridge span was removed, a barge-mounted artillery fire support base was set up so that the artillery could fire on any communist troops encountered by the engineers. A 155-mm. fire support base was also established on Highway 4, 6 km east of the bridge. For better control, the Mobile Riverine Base was moved upstream from Dong Tam to an anchorage near Sa Dec. While the 5th Republic of Vietnam Marine Battalion conducted riverine assaults in the southern portions of the area, the 4th Battalion, 47th US Infantry Regiment landed troops by helicopter in the north.

Early on 18 November both battalions encountered the communists. The Mobile Riverine Force killed 45 communists, nearly half of these by helicopter gunships, and a large medical cache was uncovered. The Mobile Riverine Force, in contrast, had only four injured. Total losses for anti-communist forces were 26 killed and 155 wounded, while the Vietcong suffered 178 killed and had 33 taken prisoner.

Second phase
Following a period at Dong Tam for rest and maintenance, the force returned to Cam Son Base area on 23 November. After the first air attack, an American B-52 strike in the heavily populated Dinh Tuong Province, the three anti-communist battalions entered the area by riverine assault craft. Few Vietcong were found and eight were killed. Several caches were discovered.

During 27–30 November operations were conducted to clear communists from the Kinh Xang Canal, which runs northwest alongside Dong Tam. Company D, 15th US Engineer Battalion, removed all water blocks along the canal while the maneuver battalions searched the Ap Bac Base area. Five Vietcong were killed and two taken prisoner; four major blocks were removed from the canal and 62 bunkers were destroyed. The opening of the upper reaches of the canal permitted the Mobile Riverine Force to use assault craft to attack the communist base in Ap Bac.

On 4 December the Mobile Riverine Base moved to Sa Dec and the 3d and 4th Battalions of the 47th US Infantry Regiment, along with the 5th South Vietnamese Marine Battalion, began operations to find and destroy elements of the 267th Main Force and 502d Local Force Vietcong Battalions in western Dinh Tuong and eastern Kien Phong Provinces. The battle that ensued on 4–5 December was one of the biggest during the Operation Coronado series.

Early on 4 December anti-communist forces encountered major elements of the 502d Local Force Vietcong Battalion in a fortified base on the west bank of the Rach Ruong Canal. The communists attacked the boats with rockets and automatic weapons and the South Vietnamese Marine battalion chose to disembark to the north of the Vietcong position. Shortly afterward the 3d Battalion, 47th US Infantry landed south of the communists. The fighting was intense and Colonel David directed the 4th Battalion, 47th US Infantry, which was at a pickup zone, to land west of the communists. In mid-afternoon, the South Vietnamese Marines made a frontal assault and overran the Vietcong's major bunker complex, supported by US helicopters. To the south the 3d Battalion, 47th Infantry, encountered resistance from scattered communist bunkers that prevented it from linking with the Vietnamese Marines.

There were 266 Vietcong killed, mostly by South Vietnamese marines. The South Vietnamese Marines lost 40 killed and 107 wounded, while the Americans suffered 9 dead and 89 wounded.

The assault craft were able to land the marines with light casualties on 4 December mainly due to a flame thrower aboard one of the armored troop carriers. A vehicle with a flame thrower had been driven aboard an ATC and fired on targets as required. The Americans believed that the flame thrower had a psychological effect on the men in the communist bunkers. On 6 December the Mobile Riverine Base moved to an anchorage on the Mekong River north of Vinh Long. After three days of local operations and maintenance work during which new fire support bases were established to support of forthcoming operations, the Mobile Riverine Force undertook operations in the southern part of Cai Be District and in the western part of Dinh Tuong Province against local Vietcong guerrillas and their installations. Initial landings were made from ATCs but later in the first day of operations, troops were brought in by helicopter. Very few communists were found.

On 14 December the Mobile Riverine Force again searched for the Vietcong in Cam Son. The Americans made assaults by boat in the southern portion of the base, followed by helicopter landings by the 3d Battalion, 47th Infantry. It was not until the last day of the operation that the Vietcong were discovered, and nine of them were killed.

On 17 December the Mobile Riverine Base moved to Dong Tam to allow the Mobile Riverine Force to land troops from the two barracks ships. By the afternoon of 18 December the American brigade and one battalion had moved ashore to Dong Tam. The USS Colleton left Vietnam to refit at Subic Bay in the Philippines and the USS Benwah moved to Vung Tau on the coast near Saigon to refit. At this time, the 3d Battalion, 60th Infantry replaced the 4th Battalion, 47th Infantry, as part of the Mobile Riverine Force, and the 4th Battalion assumed the Dong Tam defense mission.

On 19 December a two-battalion operation was initiated in northern Cai Lay District while a third battalion operated near Dong Tam. On the night of 19 December, two companies of the 3d Battalion, 47th Infantry, landed along the Kinh Xang Canal to set up ambushes. The other two battalions of the Mobile Riverine Force were landed by assault craft in the northern Ap Bac area. Effective artillery coverage was provided by the barge-mounted artillery and Battery C, 2d Battalion, 35th Artillery (155-mm. self-propelled). This operation covered most of the north-central part of Dinh Tuong Province and used both helicopters and boats to bring in troops. The Americans found few communists, killing 11. Navigability of the Kinh Xang Canal was improved during the process when engineers removed a major canal obstruction. The operation was concluded late on 22 December and the Mobile Riverine Force returned to base to conduct maintenance and prepare for Christmas truce operations.

Christmas period
The Mobile Riverine Force was instructed that only defensive actions should be taken during Christmas period and that they could fire on groups of communist soldiers who "seemed to be trying to breed contact" or who were more than "platoon-size" in number. The truce ran for 24 hours starting from 1800 on 24 December. Prior to 1800 on the 24th, one Mobile Riverine Force battalion moved to each of the two areas where saturation patrols were to be conducted. The 3d Battalion, 47th Infantry, moved to Long Dinh District, while to the southeast the 3d Battalion, 60th Infantry, moved into northern Kien Hoa Province. During the truce period there was occasional sniper and harassing fire from the communists.

The Mobile Riverine Force's next operation was in Cai Lay District of Dinh Tuong Province. On 28 December the 3d Battalion, 60th Infantry landed by aircraft and waterborne craft approximately 11 km west of Dong Tam. It conducted operations directed westward toward Cai Be, with supporting fire from barge artillery batteries located to its south along the north shore of the My Tho River. Few communists were seen during the operation; monitors and assault support patrol boats provided surveillance of inland waterways. On 29 December the 3d Battalion, 60th Infantry, continued operations to the west toward Cai Be, while the 4th Battalion, 47th Infantry, remained in the same area and destroyed 85 bunkers and captured 2 Vietcong. During the day the 3d Battalion, 60th Infantry, found only a few communists and concluded its operations in Cai Lay District.

On 30 December the 4th Battalion, 47th Infantry, was moved from Kien Hoa north and across the My Tho River to assist the 3d Battalion, 60th Infantry to continue operations in Cai Be and Cai Lay Districts. Although troops were shifted by boat, the battalions could not find large groups of Vietcong. On the following day both battalions went into positions where they stayed until the end of the New Year's truce at 0600 on 1 January 1968. In groups of platoon and company size, the battalions were dispersed to prevent the communists from using important communication lines during the truce period. Following the truce period the units arrived in Dong Tam on the afternoon of 2 January.

New year
The next major mission of the Mobile Riverine Force was an outing in eastern Vinh Long Province. On 7 January the battalions landed by air and water but found no communists until mid-afternoon, when a company of the 3d Battalion, 60th Infantry, came under heavy automatic weapons and small arms fire from an estimated two platoons of communists. Artillery support and air strikes were called in on the Vietcong, who were firing from well-prepared, concealed positions. By the end of the encounter, late on 7 January, two more companies of the 3d Battalion, 60th Infantry, were engaged. The Americans killed 28 communists and captured three weapons. The Mobile Riverine Force concluded the operation on 8 January, killing two more communists, and returned to the riverine base late that afternoon.

The Americans then targeted the 261st Main Force Vietcong Battalion in Cai Be District, in western Dinh Tuong Province. On 10 January assault craft and helicopters landed the 4th Battalion, 47th Infantry, and 3d Battalion, 60th Infantry, and by mid-afternoon Company A, 3d Battalion, 60th Infantry, was in heavy combat, sustaining moderate casualties after being landed in a communist area. Company E was flown in to support Company A as heavy fighting continued. The following day fighting was sporadic. Over the two days, the Americans killed 47 while losing 18 and suffering 50 wounded, most during the landing when they were caught out by the communists' well-prepared, camouflaged positions.

On 12 January an operation was conducted in conjunction with the 3d Brigade in Binh Phuoc District of Long An Province. The 3d Battalion, 60th Infantry, and 4th Battalion, 47th Infantry, moved by boat along the Cho Cao Canal to assigned beaches. Upon landing, American troops met heavy communist rocket and automatic weapons fire but killed 7 Vietcong. The rest quickly escaped and there was no further fighting during the two-day operation.

On 14 January the 2d Brigade embarked on the USS Benewah, and was followed aboard on 21–22 January by the rest of the Mobile Riverine Force. A cordon was set up around the village of An Quoi, near Dong Tam, by the 3d Battalion, 47th Infantry, which had the day before relieved the 4th Battalion, 47th Infantry in the Mobile Riverine Force. The cordon operation was unsuccessful in capturing or kill guerrillas, ending Operation Coronado IX.