After a long time implementing the strategy of "Vietnamization", especially their "pacification" scheme in the South, the enemy occupied most of the Mekong Delta and Tri - Thien area, pushing our main force to the other side of the border, tightening the grip of oppression of local  governments, preventing the development of our local armed forces and militia and guerrillas. By gaining certain advantages on the battlefield, the enemy subjectively assessed that their pacification program had succeeded, Northern forces had been under siege, fell into passivity, and made no progress compared to 1971. Accordingly, their strategy for the following years would be: continuing to withdraw American troops from the battlefields of South Vietnam and strengthen the armed forces of the puppet government; stepping up the pacification program to root out revolutionary secret bases and completely control the South.

On our side, promoting the victory in 1971 and in order to regain the initiative on the battlefield, make an advance for changing the war situation, the Party Central Committee decided to launch the 1972 Strategic Offensive in three directions of Southeast, Tri - Thien and the Central Highlands, among which the Southeastern front is an important coordination direction. Following the direction of the Politburo, the Southern Central Office and Military Commission launched Operation Nguyen Hue on the battlefields of the Southeastern region, in order to destroy a part of the enemy troops north of Saigon, liberate the provinces of Binh Long, Phuoc Long, Tay Ninh, Binh Duong, restore and expand the stationing areas of the Southern main force to coordinate with the main direction of Tri – Thien, create conditions for the armed forces and people of the Mekong Delta to destroy the enemy’s pacification strategy. Under the leadership and direction of the Southern Central Office and Military Command, Operation Nguyen Hue won important victories, meeting our strategic objectives, at the same time, marking the development in operational combat of the Southern main force, notably, the art of blocking in combination with attacking the enemy outside their fortifications is shown as follows:

Firstly, basing on steady posts, conduct maneuvering attacks to destroy the enemy's position. From the very beginning of the operation, in its combat determination, the Operation Command determined that: blocking the Road 13 is very important and indispensable in operational combat in order to prevent the enemy marching from the south of Binh Long town to reinforce for Loc Ninh. Accordingly, for this important task, the Operation Command selected the 7^th Division – a unit gaining many victories on the Cambodian battlefield with blocking tactic. The use of a unit with much blocking experience for the task showed the vision and creative thinking of the Southern Central Office, Military Commission and the Operation Command, and was a distinctive feature in the operation. This is because Road 13 is the shortest and easiest way for the enemy to maneuver their forces from the south of Binh Long town to reinforce for Loc Ninh. Our deployment of posts on Road 13 provided a solid support for the main force to coordinate with the local armed forces in the area of Binh Long town to attack enemy bases, and prevented the enemy from sending reinforcements to rescue Loc Ninh when this installation was under attack.

The reality in Phase 1 of the Campaign (April 1 - May 15, 1972) showed that the 7^th Division deployed its troops in a tripod formation and successfully built posts on Road 13, creating a solid position for our mobile forces to defeat the enemy’s Task Force 7’s attack at Phu Lo; ambushed and destroyed Task Force 52 at Can Le bridge when they withdrew to Binh Long town; repelled the attack of enemy’s 1^st Parachute Brigade from Chon Thanh to Ngoc Lau, and defeated their operation to rescue the 21^st Division in North Chon Thanh. In addition, the 7^th Division also coordinated with the 5^th Division to attack Loc Ninh fortress - conducting the first key battle; creating conditions for the 9^th Division to attack Binh Long town, disrupting the enemy's offensive posture. In this sense, blocking does not mean a mere passive defence, but leveraging the advantages brought about by blocking posts, mobile force actively attacked the enemy's base and marching formations, creating favourable conditions for the main force to carry out the operational key  battle. This is a creative development of the operation that made the enemy surprised, passive and defeat.

Secondly, both flexibly transform combat posture   and closely combine main blocking posts with the mobile ones to attack the enemy outside their fortifications. Although holding Binh Long town, the enemy still fell into passivity. In order to oust our main post on Road 13 and push our forces away from Binh Long town, the enemy gathered forces and means to launch large operations. Firmly grasping their intention, following the direction of the Party Central Committee and to buy time for our forces to consolidate, the Operation Command adjusted the plan for Phase 2 of the operation as "to loosen the siege of Binh Duong town, resolutely block and attack the enemy outside their fortifications, hold and attract the enemy on Road 13”. With that adjustment, we were able to both promote the effective tactic of the 7^th Division in Phase 1 and hold the enemy for a long time on Road 13, create favourable conditions for the Eastern armed forces and people to counter their pacification plan, and for the Southern main forces to coordinate with forces in the main direction of the strategic offensive to attack the enemy and win great victories. Accordingly, the 7^th Division continued their blocking task on Road 13, but not to serve our attacks but to repel and defeat the enemy's operations and counter-attacks to clear Road 13. It was the change of the blocking task that enabled us to both hold our posts firmly and maneuver to attack the enemy - a special feature of this operation. Therefore, we could both avoid the passivity in defence and promote the combat effectiveness of our posts and mobile forces.

In order to defeat the enemy's operations and hold the posts on Road 13, the 7^th Division adjusted the positions of their posts and the mobile force. In addition to holding the operational posts, the Division also expanded their area of operation, set up more mobile posts in the South of Binh Long town, and at the same time opened attacks into the flanks and rear of the enemy marching formation. To confront our new mobile posts on Road 13, the enemy had to increase their forces and means, and this was an opportunity for us to manoeuvre and attack on the flanks and rear of their marching formation. With the transformation of the position of main and mobile posts when attacking the enemy outside their fortifications, we not only held the operational posts firmly, but also defeated all efforts of the enemy to clear Road 13.

Thirdly, flexibly apply tactical forms and combat tactics. Confronting the enemy with superiority in terms of strength, firepower and high mobility requires the Operation Command to both decide on the appropriate tactical forms and continuously adjust combat method on Road 13 to defeat the enemy's plots and hold the post. Accordingly, in addition to the initial combat method which concentrated forces and means to break into the enemy’s stronghold, attack their reinforcements and destroy their installations, the Operation Command also promoted the power of the posts to create a fulcrum for mobile forces to attack the enemy outside their fortifications. However, in each battle and each post, the operation’s maneuvering forces also coordinated with friend units, local armed forces and posts to block and split the enemy's marching formations, then launched ambushes, engaged their front together with ambushed into the flanks and rear of their marching formation.

Practically, in the attack to block the march of the enemy’s 21^st Division to Binh Long town (from 19^th to 23^rd May 1972), with close attacks, the 7^th Division coordinated with the 205^th Regiment to encircle, isolate, ambush, and destroy 01 armored detachment entirely and heavily damaged another regiment of the enemy, forcing them to withdraw to Chon Thanh. During the counter-attacks against the enemy on Road 13, relying on the solid position of the posts, the Operation’s mobile forces engaged the enemy’s front and ambushed their flanks and rear, making them totally surprised and unable to respond. When the enemy abandoned Loc Ninh, we held an ambush and destroyed their entire 52^nd Brigade in Can Le. With the flexible application of tactical forms, we destroyed their Loc Ninh and Xa Mat strongholds in a short time, blocked and defeated their operations to clear Road 13.

The victories won in Operation Nguyen Hue not only changed the situation on battlefield, created a firm foothold for the Southern main force , but also made significant contribution to the 1972 Strategic Offensive. Victory of the operation marked the development of operational offensive art on the Southern battlefield, especially the art of blocking in combination with attacking the enemy outside their fortifications - a valuable lesson that needs to be studied and applied in the cause of national defence today.

Senior Colonel, Assoc. Prof.  NGUYEN VAN SAU, PhD, Deputy Director of the Vietnam Military History Institute