50 years ago, with the victory of Nong Son – Thuong Duc Operation, we annihilated a significant portion of enemy troops and shattered their defensive network on Quang Da battlefield. This crucial victory marked a significant development in the art of joint combat, including the art of launching operational-level key and decisive battle, contributing to creating posture and momentum for the 1975 Spring General Offensive and Uprising.

At the turn of 1974, facing our powerful attacks, the enemy began to show signs of weakness in their position and force across the Southern theatre of war. Their schemes to implement a plan for “overrunning the territory” and erasing the “leopard skin” posture on the battlefield via “pacification” measures after the signing of the Paris Accords were on the brink of collapse. Their tendency to abandon peripheral outposts to concentrate their force on major fortifications became increasingly evident. On Quang Da battlefield, to protect the western gateway of Da Nang military complex, the enemy constructed the key outpost of Nong Son - Thuong Duc garrisoned by elite and battle-hardened units and amassed a large quantity of modern weapons and equipment in this area in combination with fire power of air and artillery forces on standby to prevent our attacks from afar. Relying on the rugged terrain and thorough preparations, the enemy arrogantly declared: “Only when Vu Gia River flows backwards will the South Vietnam liberation army occupy Thuong Duc”.

Our troops victoriously occupy Thuong Duc military sub-zone

On our side, successive victories on various battlefields had opened up the possibility of inflicting major destruction on the enemy’s main forces. To create advantageous conditions and opportunities for 1975, following the directive of the Central Military Commission, Military Region 5’s Party Committee and Command advocated launching a series of Autumn - Winter operations and selected Quang Da as the main area of combat. With the determination to drive the enemy out of key areas, opening up the transportation corridor from the mountainous region to Quang Nam - Da Nang plain, and simultaneously creating favourable conditions for strategic operations in the dry season of 1974 - 1975, we decided to launch Nong Son - Thuong Duc operation. Thanks to high combat determination, excellent execution of key decisive battles, close coordination with local armed forces, and the uprisings of the people in the operational area, we continuously attacked, inflicted heavy casualties on the enemy, shattered their defensive network, and expanded our liberated areas. This significant victory enabled us to accurately assess the combat strength of Saigon puppet government’s main forces after the withdrawal of US troops, thwart their plans to capture more land and population, create new posture and momentum for us in the theatre of Military Region 5, and further pressure the joint military base of the enemy in Da Nang. This was a major victory both militarily and politically with the highlight of the art of launching key and decisive battle.

First, thoroughly grasping situational developments and correctly selecting the target for a key and decisive battle. Based on a comprehensive grasp of situational developments, we identified the military sub-zone of the district of Thuong Duc as the target for our attack. This was an absolutely correct decision, reflecting the creative thinking in target selection by the Operation’s Command. This fortification was a crucial “link” and “outpost” in the Southwestern defensive system of the Da Nang military complex and considered to be the “bulwark” in the adjoining area to block our transportation corridor from the mountainous region to Quang Nam – Da Nang plain via Vu Gia River and Route 14B. If Thuong Duc were levelled, we would gain favourable posture and strengths for breaking the enemy’s defensive network in the adjoining areas, opening up the door to Da Nang, and creating favourable conditions and opportunities for chain reactions that would significantly impact on the military scenarios in the central and northern parts of Central Highlands. Taking full control of Thuong Duc would secure our transport route from the mountains to the coastal plains of Central Vietnam. Recognising the importance of Thuong Duc, the enemy spared no efforts to fortify it heavily. Yet, geographically, located deep in our liberated areas and cut off by Con and Vu Gia rivers, this fortification still exposed fatal weaknesses, making it easy to be isolated when being attacked. In addition, our interlocking battle posture was a major challenge for any reinforcement and rescue attempt by the enemy. Therefore, we had favourable conditions to isolate the area both operationally and tactically, focusing on fully destroying each cluster of fortifications and liberating each zone one by one. Furthermore, when attacking the military sub-zone of the district of Thuong Duc, we were able to take advantage of the rugged terrain to secretly make preparations and deploy our troops and equipment, as this densely forested area bordered our western base. Capturing Thuong Duc would pose a direct threat to Da Nang military complex, luring a major portion of enemy troops, allowing our troops and people in other areas to rise up and counter-attack, thwarting the enemy’s siege, and expanding our liberated zones. Hence, selecting Thuong Duc as the target for the key and decisive battle of the Operation was a precise decision, targeting a critical link of the enemy’s defensive network. The realities of the Operation showed that the enemy suffered heavy losses as a result of our continuous attacks. We quickly took control of Thuong Duc, promptly rearranged our formation, defeated the counterattack of the parachute division under the enemy’s strategic reserves, and pushed them deeper into strategic passivity.

Second, concentrating superiority in manpower and firepower to ensure victories and flexibly and opportunely transform battle posture. As the most important base of the defence system in southwestern Da Nang, the enemy not only deployed elite, battle-hardened units to Thuong Duc, but also constructed a robust system of fortifications with strong firepower and multi-layered barbed wires and dense minefields, creating an inter-connected defensive network. In addition, the firepower of air force and artillery units of the enemy’s 1^st Tactical Region was always on standby to provide maximum support to thwart our attacks. Therefore, to completely destroy this key stronghold, we had to concentrate overwhelming superiority in manpower and firepower, flexibly transform combat posture, and promptly respond to combat incidents. Accordingly, for the sake of victories, we used our infantry forces three times larger than the enemy’s and concentrated a superior artillery force with continuous bombardment. Furthermore, we opportunely deployed a Malyutka ATGM company to quickly destroy gun emplacements, bunkers, and firing positions in the bridgehead area, thereby effectively supporting our infantry units in combat to gain victories.

Given rapid situational developments, to defeat the enemy’s combat schemes, we promptly transformed combat posture for proactive assaults. In the first and second phases of the battle, due to our inappropriate choice of tactics and incorrect identification of the primary attack directions, our combat performance was limited. Closely monitoring the battle in progress, the Operation’s Command opportunely adjusted forces and equipment and switched the tactics into four stages: first, annihilating the enemy at Ha Tan station and outpost C; second, annihilating the enemy at the military sub-zone and the security station; third, destroying the enemy at the district; fourth, eliminating the remaining enemy forces at Ha Tan. During combat, we promptly adjusted our plans, switching the secondary attack directions to the main ones, shifting from swift attacks to steady advance. Along with that, we promptly adjusted firepower, quickly moving the 85mm artillery fortifications from Height 118 to Height 296 (about 1 km from the enemy’s position) to directly bombard the enemy’s system of entrenched fortifications and provide more effective support for infantry attacks. This move completely caught the enemy off guard and led them to defeat. As a result, although the enemy relied on their system of entrenched fortifications to fiercely resist, thanks to the power of joint assault and flexible, timely combat posture transformations, we levelled the military sub-zone of the district of Thuong Duc and undermined the enemy’s every effort to recapture this important base.

Third, closely coordinating different forces in combat area, promoting synergy to attack the enemy. The attack on Thuong Duc involved many forces, so the Operation’s Command emphasised close coordination between units and forces right from the beginning and throughout the Operation to create synergy to attack the enemy. When attacking Thuong Duc, regular units coordinated closely with local armed forces to establish a thorny battle posture from the very start, which enabled our forces to position themselves to quickly besiege and isolate Thuong Duc, cutting it off from Da Nang and other clusters of fortifications. To this end, Artillery Battalion 575 of the Provincial Military Command used recoilless guns to bombard Da Nang airport, destroying 11 aircraft; the 2^nd Local Battalion besieged Kien Thiet post in Dien An commune, and the masses rose up to dismantle concentration areas, overthrow the puppet government, and eliminate the enemy’s spies and collaborators in many localities. In Quang Nam, the 10^th and 7^th Local Battalions captured Gia Moc Xa, Hon Giang, Hon Dun, etc.; guerrilla forces in Son Thang and Son Long communes attacked the enemy’s militia platoons; Que Son district’s sappers demolished Xuan Phuoc bridge, putting the enemy’s forces in Thuong Duc in an isolated, passive, and confusing situation. To enhance our combat strength, air defence and artillery forces closely coordinated and effectively supported Division 304 to promptly deploy and engage on all fronts, resulting in the destruction of 13 enemy aircraft, 3 M113 APCs and many bunkers and firing positions. Thus, thanks to the close coordination among all forces in the combat area, we created superior synergy, quickly establishing a favourable combat posture from the very beginning, continuously attacking and promptly defeating the enemy’s tactics.

The key and decisive battle aimed at liberating the military sub-zone of the district of Thuong Duc contributed to the overall success of the Operation, shattering the enemy’s defensive network in southwestern Da Nang, and shaping new combat posture for our forces in the operational area of Military Region 5. Invaluable lessons drawn from the art of launching the Operation’s key and decisive battle remain precious today. They need to be further studied and creatively applied in a war of defending the Fatherland.

Colonel NGUYEN VAN PHUC, PhD

Infantry Officer College No.1