In early 1972, implementing the strategic plan, we launched the Tri – Thien Offensive Campaign by large scale combined arms. The campaign smashed the enemy’s hard defensive line and totally liberated the province of Quang Tri, changing the complexion of the war with distinctive features of operational offensive art.

Though suffering from continual failures in the Indochina battlefield, the US imperialists and the South Vietnam regime still pursued their “Vietnamization” strategy with the aim of improving their position at the Paris Peace Conference. Implementing their intention, they strengthened their defensive line in the Tri – Thien direction, the front line in their defensive system which had been built firm, strong, inter-connected and inviolable. The enemy troops at the line included two infantry divisions, two marine brigades, three  armor battalions, 17 artillery battalions, etc with air and artillery support, aiming to  preventing and defeating any assaults.

Regarding our side, implementing the attempt of gaining the decisive victory in 1972, the Politburo decided to launch a strategic offense through out the South with Tri – Thien battlefield being the main direction. It was the biggest combined arms campaign  at that time. After nearly 3 months of combat, under the sound leadership and direction of the Central Military Commission, the campaign ended successfully, killing and holding over 30,000 enemy troops, destroying and capturing a great deal of weapons and equipment, totally liberating Quang Tri province, contributing significantly to the victory of the Strategic Offensive in 1972. This victory left us a number of valuable lessons of the art of directing an offensive campaign, including the distinctive art of combined arms operations .

1. Creating steady and dangerous battle disposition; properly deploying weaponry and vehicles ensuring secrecy and surprise for the decisive fight.

The Tri – Thien 1972 Offensive Campaign took place near the Northern rear so we were able to make thorough preparations for it. However, we still faced a number of challenges, namely the wide area of operation, the strong and multi-layer defensive line of the enemy with the control of McNamara Line night and day. Moreover, to strengthen their defense, the enemy supplemented several modern kinds of weapons and vehicles, such as artillery, air forces, gunboats, even  B-52 strategic bombers, etc. Meanwhile, in order to create the disposition, we had to deploy a large number of troops, weapons, equipment, particularly heavy vehicles. To settle the problem, on one hand, the Campaign High Command made full use of the strategic disposition to develop operational disposition steadily. On the other hand, they coordinated closely with local troops to promptly build maneuvering routes, particularly those for  heavy vehicles such as tanks, artilleries, missiles, etc. Thanks to these routes, our forces, particularly, mechanized ones, were secretly maneuvered to the field and formed up safely. By implementing synchronously a number of measures, we deployed a large number of troops and weapons to all four attacking directions with a width of hundreds of kilometers safe and sound. This was the biggest achievement that has never done before. What’s noteworthy was that right by the McNamara Line, our main divisions freely carried out their preparations and got ready for the operation without the enemy’s notice. Later, researchers all held that it was the fast and secret maneuver and deployment of troops, weapons and vehicles that made it easy for units to make all round preparation, actively engage the enemy and gain victory.

2. Combine fire power closely with manpower  and swooping power in the main direction, creating an overwhelming strength and carrying out inward assaults.

The enemy at the Tri –Thien battlefield was strong at the front but weak at the rear. At first, we intended to choose Southwestern region of Quang Tri as the main direction as the enemy there was rather weak and unattended. However, at this direction, it was hard for us to deploy huge amount of weapons and vehicles for big attacks. After thorough assessment of the enemy, our troops and the area of operation, the Campaign High Command decided to attack into the enemy’s front. This took the enemy by surprise as they did not think we could launch big assaults in Quang Tri. This is the first time in the war we launched a large scale offensive campaign with combined arms strength attacking the enemy’s most powerful line which surprising and shocking them. At the onset of the campaign, our artillery forces fired nearly 8,000 rounds, totally controlling 24 enemy’s bases, including their 13 artillery positions, annihilating many enemy troops and destroying many military establishments of them. Seizing the opportunity, infantry and tanks synchronously advanced in all directions, occupying the targets of Dong Toan, Ba Ho, the 544 Height, etc. Particularly, the 126 Commando Regiment of the Navy opportunely advanced and completely destroyed the enemy troops on river and in their Coastal Battalion 11 based at the Cua Viet Port, completely controlling river routes in the East. With the art of employing combined arms operations seriously and creatively, within only 5 days, the campaign totally smashed the outer layer of the enemy defensive line, destroying the McNamara Line and liberating the two districts of Gio Linh and Cam Lo, and forcing Sai Gon regime to send immediate reinforcements for the Quang Tri front.

3. Flexibly and creatively employing the strength of combined arms to defeat the enemy new defensive tactics. Losing the outer line and being heavily damaged, the enemy hastily sent in reinforcements and adjusted their disposition to stop our advance. Accordingly, they organized defensive groups of battalion and regiment levels which were closely connected, supported by gunboat and air force fire with tanks and armors being the core, making stationary defensive areas together with flexible mobile forces in the main and secondary countering lines to cope with us. This was their new trick while we were unfamiliar with these flexible groups hence facing numerous difficulties. To find out the right solution to the problem, the Campaign's  High Command organized buffer combat operations to review and find out the right combat method. Accordingly, we could no longer launch quick and massive attack to defeat the enemy’s mobile groups but use a series of assaults to partly break the enemy and then hold a decisive battle to destroy large number of the enemy. Implementing the new combat method, the campaign focused on upholding the power of modern weapons as both continuously holding strike to destroy the enemy tanks and armored vehicles and attacking the main targets all across the line; surrounding and separating the enemy, partly breaking the enemy line and gradually annihilating completely the enemy.

The Tri – Thien Offensive Campaign  in 1972 was victorious and of strategic significance, positively affecting our strategic offense in the whole southern battlefield in 1972. Victory of the campaign represented a new development the art of combined arms operations. This is a valuable lesson which needs further study and employ in the war to safeguard the Fatherland.

Snr Col. Pham Duc Truong, MA

Vietnam Military History Institute