Operation Truong Cong Dinh

Operation Truong Cong Dinh, which occurred in March 1968, was an initiative of the United States and South Vietnamese military to sweep the area surrounding the Mekong Delta town of Mỹ Tho in the south of Vietnam to root out Viet Cong forces in the area, and to stop them from attacking traffic on the nearby Highway 4. The operation started on March 7, 1968, and lasted almost four weeks, involving the 1st and 2d brigades of the US 9th Infantry Division and the 7th Division of the Army of the Republic of Vietnam backed by South Vietnamese Regional Forces. Operations were supported by an American artillery battalion, which established a fire support base on the north bank of the Mỹ Tho River, and the Mobile Riverine Force which conducted a series of riverine and airmobile operations. The heaviest action occurred on the first two days; five US helicopters were shot down on the first day, and two artillery barges were sunk the day after.

Background
Trương Công Định was a 19th-century mandarin who served under Emperor Tự Đức of the Nguyễn Dynasty and operated in the Mekong Delta. He gained fame after the initial French invasion of southern Vietnam in the late 1850s for leading nationalist resistance fighters and was well known for his guerrilla attacks on French units along the waterways of the Mekong Delta. In 1862, faced with serious internal rebellions in other parts of the country, Tự Đức decided to cede three southern provinces to become the French colony of Cochinchina so that he could focus on putting down internal revolts. Trương became more iconic after this for his condemnation of the cession and his defiance of the emperor in continuing to fight.

Operation
The objective of Operation Truong Cong Dinh was to destroy communist forces in Dinh Tuong Province (the province surrounding the regional delta centre of Mỹ Tho) and to reduce the communist threat west of Mỹ Tho, which focused on harassing traffic on Highway 4. Today this is known as National Route 1A and traverses Vietnam from Cà Mau in the far south to China in the north; the part in question in this operation headed westward out of Mỹ Tho before turning south and heading deeper into the Mekong Delta towards Cần Thơ, the main center in the delta, before proceeding to Cà Mau. The operation started on March 7, 1968, and involved elements of the 1st and 2d brigades of the US 9th Infantry Division and the 7th Division of the Army of the Republic of Vietnam backed by South Vietnamese Regional Forces. This was the first time that the commanding general of the 9th Infantry Division was able to use the 2d Brigade in a continuing co-ordinated role with another brigade. The Mobile Riverine Force conducted a series of combined riverine and airmobile operations, beginning east of Mỹ Tho. Operations were supported by the 3d Battalion, 34th Artillery of the US, which established a fire support base on the north bank of the Mỹ Tho River, 16 kilometers east of the city.

During initial airmobile assaults on 7 March, communist resistance was light and no major firefight resulted. During the afternoon, the two battalions shifted their area of operations west-northwest of Mỹ Tho in response to intelligence reports. At 19:20 the 4th Battalion, 47th Infantry of the US came under heavy small arms and automatic weapons fire just west of Mỹ Tho. This continued until 22:25. The following day anti-communist troops met no Viet Cong in the area; in response to new intelligence the two battalions moved again at noon into the area of operations of early 7 March. There were several firefights during the rest of the day. The most significant occurred at 17:15 when Company B, 4th Battalion, 47th Infantry, made an assault landing by helicopter and was fired upon by a Viet Cong force from well entrenched positions along the southern edge of the landing zone. Five helicopters were brought down during the first landing. Throughout the evening and into the night, as other elements of the two battalions maneuvered in support of Company B, there was sporadically heavy fighting in the area. At 03:00 the fire support base was attacked by mortars, sinking two artillery barges carrying four 105-mm howitzers. The anti-communist infantry continued their sweep of the previous day's battlefield without finding any Viet Cong and returned by Armored troop carriers (ATC) to the Mobile Riverine Base at Dong Tam in the late afternoon.

On March 10 the Mobile Riverine Force shifted operations to near the towns of Cai Lậy and Long Dinh in Dinh Tuong Province. Troops of the 1st and 2d Brigades, of the 9th US Infantry Division, conducted day and night patrolling and reconnaissance against suspected Viet Cong locations along Highway 4 until March 16, when the 1st Brigade was withdrawn. On March 18, boats of US River Division 92 received heavy automatic weapons and rocket fire from the communists while patrolling west of Dong Tam. The rockets damaged several assault support patrol boats and one monitor. The operation continued without opposition the next day, and the infantry battalions returned by ATC to the Mobile Riverine Base near Dong Tam.

On 22 March the Mobile Riverine Base, still located in the Mỹ Tho River south of Dong Tam, was attacked at 03:20 by communist forces using mortars and recoilless rifles. The USS Benewah (APB-35) received two 75-mm recoilless rifle hits that caused minor damage, and near misses were registered by Viet Cong mortars on a landing ship tank, the USS Washtenaw County.

For the rest of March the Mobile Riverine Force continued operations in Dinh Tuong Province with occasional light to moderate firefights. On 1 April the 3d Battalion, 60th Infantry of the US left and assumed the Dong Tam security mission and was replaced in the Mobile Riverine Force by the 3d Battalion, 47th Infantry. Operation Truong Cong Dinh ended on 2 April, after a single-battalion airmobile operation in Ham Long District in adjacent Kien Hoa Province, just south of Dong Tam.

During the operation, the Mobile Riverine Force used extensively a riverine assault reconnaissance element, a small unit first employed in December 1967 that consisted of three or four monitors and several assault support patrol boats. The riverine assault reconnaissance element led ATC convoys and employed reconnaissance by fire against likely Viet Cong ambush positions. According to the US military, the technique reduced casualties because of the firepower and mobility of the craft in the riverine assault reconnaissance element and the placement of ATCs carrying infantry in the rear of the column. Airmobility was used during the operation to increase the flexibility of the Mobile Riverine Force by providing increased intelligence, firepower, and escort coverage for convoys during troop movement.