The “pincer movement” to invade and annex Dai Viet (fighting down from the north, fighting up from the South) was the deep-seated conspiracy of Chinese feudal dynasties. This plot was used by the Song Dynasty in the second war to invade our country (from 1075 to 1077), but smashed by the Ly army and people.

In the late 1060s (11^th century), the Song feudal state (China) was deeply sunk into fierce social conflicts. Political factions contended with each other throughout localities and within the court. The "revolution" to revive the Song Dynasty was conducted by the New Party of Chancellor Wang Anshi but strongly opposed by the Former Party of former Chancellor Si-ma Guang and fierce sabotage of the landlords and traders. In the northern border, the two countries, Liao and Xia, tried to threaten the territory, encroach on land, thereby provoking crisis, making the Song Dynasty more confused and difficult to take control.

In the history of Northern feudalism, in good and bad times, the authorities often thought of inventing a glorious martial art to master the public opinion and heighten its image. This was the case for the Song Dynasty (during the reign of Shenzong Emperor). Being incapable of pacifying Liao and Xia in the North, they devised a method of "killing the chicken to scare the monkey" by planning to invade Dai Viet in the South. By conquering Dai Viet, the Song Dynasty would raise its status, thus frightening the countries of Liao and Xia. At the same time, it would provide the basis for the New Party to "show the effectiveness of its reform," creating an overwhelming force to dominate the former party in the court. With that "killing two birds with one stone" tactic, the Song Dynasty (headed by King Song Shenzong and the Chancellor Wang Anshi) put all efforts in preparing the second war to invade our country. The Song Dynasty’s conspiracy to invade Dai Viet was made this time with a plan of "pincer movement." Accordingly, on the one hand, the Song secretly built military and logistics bases in the area bordering Dai Viet’s North and Northeast as the starting point for the army's invasion from the North. On the other hand, the Song’s King tried to bribe Zhancheng and Chenla, enticing the kings of these countries to attack Dai Viet from the South. According to the old Chinese history, "Zhancheng and Chenla had a feud with Jiaozhi. Song’s King ordered Xu An Xiao and Liu Sheto recruit some sea merchants, trying to entice the kings of those countries to attack Jiaozhi. After pacification, the reward would be given. "

In high spirit of vigilance to protect the country and firmly grasp the situation in all aspects, Ly Nhan Tong, King of Ly Dynasty, and the famous General Ly Thuong Kiet met with courtiers to discuss and devise an appropriate strategy aimed at "pacifying Zhancheng, destroying the Song," smashing the vicious conspiracy of the Song aggressors’ pincer movement in Dai Viet.

Firstly, gathering a large force to carry out the decisive attack and break the southern pincer. In the southern border area of ​​Dai Viet, Zhancheng troops caused constant disturbance, especially after the support and encouragement of the Song Dynasty, Zhi Ju - King of Zhancheng became increasingly aggressive and sent troops to invade the border of Dai Viet. They even crossed the sea to go deep into Nghe An and ready to collaborate with the Song Dynasty, making an intention of expanding Zhancheng territory to the North. Understanding the enemy's conspiracy, King Ly Thanh Tong immediately announced "the fight against Zhancheng" in order to defeat the Zhancheng army in the South before the Song Dynasty intruded from the North. In 1069, the King himself and Ly Thuong Kiet led an army of 50,000 and actively launched an attack on Zhancheng. Despite initially facing difficulties, with a strong determination, a talented commander and a superior force compared to the enemy, Dai Viet troops conducted fierce attacks, one after another, defeated Zhancheng Marine at Nhat Le gate, then smashed the enemy's defensive line in Tu Mao river, afterwards directly attacked Zhancheng capital, captured Zhi Ju and brought him to Dai Viet (later Ly Thanh Tong returned him home). Even so, the king of Zhancheng was stubborn and refused to surrender. In 1074, enticed again by the Song Dynasty, Zhancheng army kept destroying Dai Viet border. This created a favorable condition for the Song Dynasty’s invasion. As a result, the Song Dynasty hurriedly prepared a war, urgently mobilized forces, boats, rafts and transported food to the bases near the border. In order to cope with the impending invasion, in September 1075, Ly Thuong Kiet continued to send troops to patrol the South, persuaded Zhancheng people, redrew the map of rivers and mountains, renamed three areas: Bo Chinh, Lam Binh, Minh Linh; at the same time, built more posts, strongholds and encouraged a great number of Dai Viet people to live with Zhancheng ones, with the aim of turning the land of conflicts into a peaceful one in the South of the country. Thus, by adopting the initiative to defeat Zhancheng military forces and eliminate threats (in 1069), organizing careful defence, creating stability in the southern border region, the Ly dynasty broke the Song plot to collaborate with Zhancheng troops. The southern "pincer" was destroyed, enabling the Ly Dynasty to concentrate on defeating the Song's major pincer from the North.

Secondly, strengthening national unity, encouraging the chiefs of ethnic minorities in the Northern mountainous areas to actively fight against foreign aggressors. Despite the Song's conspiracy to entice the heads of ethnic minorities in the North of our country, the Ly dynasty always put belief in the loyalty and submission of the chiefs. Ly’s King still let them continue to govern their localities as before, accepted their rights and status, even conferring great titles and high ranks on them. Many powerful rulers also got married to princesses, forming family ties, etc. Those actions had a strong influence on preserving security and protecting the territory on the border. In particular, during the second war against the Song invaders, the Ly dynasty mobilized thousands of ethnic minority soldiers to join the resistance war for the defence of the country.

The history proved that Dai Viet troops’ success in actively attacking Weng Zhou, Qin Zhou, and Lian Zhou in late 1075 and early 1076 as well as in the whole war against Song invaders was achieved by close association and synergies between the imperial force and the local armies of the chiefs, such as Tong Dan, Than Canh Phuc, Hoang Kim Man, Luu Ky, Vi Thu An, etc. Army groups from mountainous areas, under the direct command of the local chiefs,  had successfully completed the pioneering tasks of raiding and destroying depots, logistics stations, and the starting point for the Song army invasion right on their land. When the Song army set foot on Dai Viet land, these armies took advantage of the rugged terrain, continuously prevented and caused loss to the enemy forces. When the enemy crossed the defensive line, the groups fought backwards, cutting off the supply lines. Notably, the army and people of ethnic minorities in Lung Chau, led by Than Canh Phuc, made a number of excellent feats, stopping Guo Kui’s army on Quyet Ly battlefield, Giap Khau (currently Chi Lang district, Lang Son), inflicting great damage to the enemy. On Quang Nguyen front, chief Hoang Luc from Luong Dinh commune (Trung Khanh, Cao Bang) commanded troops and local people to stop the enemy from the border. When they passed the ambush site, heading to Bac Giang, Hoang Luc's army continued to fight and destroy them from behind.

Thirdly, mobilizing the strength of the entire people to the defensive line in Nhu Nguyet river, breaking the main “pincer” of the aggressors. Right after returning the victorious army from Song land, on the basis of reliable intelligence sources on the enemy situation and with the help of the people, Ly Thuong Kiet decided to build a defensive line on the Southern shore of Nhu Nguyet river to stop the invasion of Song Dynasty. With the goal of turning this place into a strategic battlefield, Nhu Nguyet river defensive line had sprung up in such a short time. This not only presented a great military construction of our army and people in the 11^th century, but also showed the excellent strategy of Ly Thuong Kiet in the selection of the place to destroy the enemy and the ability to mobilize the strength of the entire people to fight against foreign invaders. Reality proved that the value as well as the solidity of the defensive line in Nhu Nguyet river symbolized an ingenious combination of a rugged terrain with strongholds, obstacle yards and active defensive thought of Ly Thuong Kiet in organizing and using the army reasonably as well as promoting the strength of each force. Therefore, throughout the combat, our army always promoted the effectiveness in preventing the enemy on a large scale and maintained defence in a deep and focalized manner. Close cooperation was ensured between the main army of the court and the militia and local forces to fight the enemy both in front, behind, on the flank, gradually pushing them into passive position. With the solid line of defence, Ly Dynasty’s army and people blocked the Song’s advance, defeating the plan of “quick fight, quick victory,” forcing them to get bogged down into the battle. Simultaneously, all possibilities were considered to confine the enemy in a certain space, turning time into force, delving into the difficulties and disadvantages of the invaders, firmly grasping the opportunity to conduct decisive counter-attacks with the aim of exacerbating the enemy’s exhaustion. In March 1077, the main “pincer” of the Song army in Dai Viet invasion war was broken, and the enemy hurriedly retreated, stepped on each other to escape. After the first Song’s defeat, the “pincer movement” plot of aggressive Northern feudal forces to invade Dai Viet kept going, but all ended in failure.

Senior Colonel Nguyen The Mau, PhD

Vice Dean of the Local Military Faculty, National Defence Academy