The battle of Rach Gam - Xoai Mut in 1785 is one of the most remarkable riverine clashes with its resounding victory in the national history of fighting against foreign aggression. With his military genius, Nguyen Hue creatively, effectively employed various combat methods and strategies and perfectly dealt with the military art-related issues to completely defeat the large-scale attack by Siam’s Army.
Responding to Nguyen Phuc Anh’s call for military intervention, in the summer of 1784, the King of Siam ordered two generals, Chieu Tang and Chieu Suong, to command 20,000 naval soldiers and 300 warships to invade our country. To ensure a total victory, the King of Siam also ordered two other generals, Luc Con and Sa Uyen, to command 30,000 infantry troops to attack our country. Those armies were continuously reinforced by Nguyen’s main force.
However, constant defeats of Nguyen’s Army against Tay Son’s Army partly forced Siam generals to take a cautious approach. Thus, in their invasion of Dai Viet, Siam-Nguyen generals decided to conduct operations, strengthen their force, and quickly deal with the situation at the same time. Under that direction, after launching the invasion, the Siam-Nguyen coalition landed on and occupied Rach Gia, instead of Gia Dinh citadel, in order to build the latter into a strategic outpost for providing military supplies, attacking Tay Son’s Army, and withdrawing their troops. Given a powerful naval force and means of war, the attack by the Siam-Nguyen coalition was very slow. Within 3 months (from July to October 1874), they just arrived in Can Tho, occupied Ba Xac and Tra On stations, and stopped at Sa Dec.
In response to the enemy’s invasion, Tay Son’s general Truong Van Da in Gia Dinh citadel deployed the naval force from Gia Dinh to Long Ho (the present-day province of Long An) to halt the enemy, while ordering Colonel Dang Van Tran to return to Quy Nhon and report the scene. In spite of being incapable of defeating the offensive by the Siam-Nguyen coalition due to the too large difference in force, Tay Son’s troops resolutely fought to defend Long Ho which was opposite the Siam-Nguyen coalition’s base in Sa Dec with a view to blocking the force movement by Nguyen Anh and Siam generals. In Quy Nhon, after receiving the urgent information from Gia Dinh, Nguyen Hue and his generals, namely Vo Van Dung, Tran Quang Dieu and Bui Thi Xuan immediately commanded 20,000 seasoned soldiers to fight the enemy. In early 1785, troops of Tay Son landed on and garrisoned My Tho. In that area, while dispatching a team to grasp the enemy’s situation, Nguyen Hue paid special attention to studying and assessing the scene. Doing so enabled the young talented general to comprehend the invaders’ nature after their initial victories, particularly realise the tension caused by Siam Army’s disrespect for Nguyen Anh and the disagreement between the people of Gia Dinh and Siam Army due to the enemy’s brutality and suppression, and correctly evaluate the terrain (the enemy’s stationed position) and the advantages and difficulties when he conducted operations in the riverine area. Those moves provided an important scientific basis for the Command of Tay Son’s Army headed by Nguyen Hue to make a decision on the combat strategy. More specifically, the Command of Tay Son’s Army decided not to directly attack the enemy’s naval base in Sa Dec. Instead, Tay Son’s Army would drag the enemy out of their base, entice them to enter our favourable selected area, and secretly concentrate its force to launch an offensive and destroy all naval troops of the Siam-Nguyen coalition.
To realise that determination, first of all, Nguyen Hue and the Command of Tay Son’s Army made best use of the terrain and secretly established a posture to fight the enemy. This is a noteworthy feature of the military art and a principle of victory in combat. It is certain that when we take advantage of the terrain, organise force and means closely and scientifically, establish an inter-connected posture to “herd, split up,” and attack the enemy’s troops in all directions, they would fall into passivity and panic. Fully aware of that strategy, Nguyen Hue decided to select the river of My Tho, from Rach Gam to Xoai Mut, as the theatre of war to launch a decisive fight against the enemy. This stretch of the river is about 7 km long and the river bed is large enough to herd hundreds of the Siam Army’s warships. Besides, Nguyen Hue, a military genius, discovered that the rivers of Rach Gam, Xoai Mut, Truoc and Sau, the banks of My Tho river, and the My Son islet would create favourable natural elements for fighting the enemy. Thus, Nguyen Hue made best use of the terrain to set up an ambush. Tay Son’s naval troops and warships were concealed in the rivers of Rach Gam, Xoai Mut, and Sau while its artillery and infantry troops were secretly deployed along the banks of the My Tho river and on the Thoi Son islet. When the Siam-Nguyen troops entered the Truoc river, Tay Son’s naval force came forth from the small rivers of Rach Gam and Xoai Mut to block and herd the enemy’s warships into the selected area. At the same time, Tay Son’s artillery force shot straight at Siam-Nguyen’s warships and cooperated with the infantry force in attacking the enemy’s formation and dividing the enemy’s warships into parts.
Second, creating a diversion to entice the enemy into the prepared theatre of war and annihilate them. There is a fact that the enemy concentrated a rather large force in the area of Sa Dec, with 20,000 Siam troops, 300 warships, and several thousands of Nguyen troops; therefore, it wouldn’t be easy for Tay Son’s Army to win against the enemy. The area occupied by the enemy was at the head of the Tien Giang river, which enabled Siam’s warships and troops to move quickly and easily conduct operations. In other words, it was disadvantageous for Tay Son’s Army to directly attack Sa Dec. Against that backdrop, Commander Nguyen Hue established a diversion to drag the enemy out of their base and entice them into the prepared area with a perfect diversion plan which had been thought to be their following combat plan by Siam-Nguyen generals.
After preparing the battlefield, Nguyen Hue deployed a section of naval troops to frequently provoke the enemy in Sa Dec, while dispatching a group of warships to form a line across the rivers of Rach Gam and Xoai Mut so as to lure the enemy. Being subjective and reliant on their strength and advantages, Siam generals hoped to both hunt down Tay Son’s troops and occupy My Tho. On January 18th 1785, all naval troops of the Siam-Nguyen coalition were ordered to sail along the My Tho river and hunt down Tay Son’s naval force. Troops and warships of Tay Son both weakly retaliated against the enemy and withdrew from the area. Siam generals believed that all troops and warships of Tay Son had appeared. Without any hesitation, Siam generals urged their troops to sail after Tay Son’s warships. Thanks to the advantages in wind and current in the My Tho river, Siam’s troops and warships en masse hunted down Tay Son’s naval force. When it got dark, the enemy’s warships kept following the light from Tay Son’s warships to hunt down and advance towards My Tho, without knowing that while withdrawing to lure the enemy, Tay Son’s warships gradually turned off their light and hid themselves in the river corners. After reaching the area of Rach Gam and Xoai Mut, the enemy saw some of Tay Son’s warships only. Knowing that they had been caught in a trap, Siam-Nguyen’s naval troops had no choice but to fight against the strong attack from Tay Son’s troops.
Third, ambushing the enemy and manoeuvring to annihilate them. As expected, Siam-Nguyen’s warships were lured into the area selected by Tay Son’s Army. To commence the battle, two teams of Tay Son’s naval troops suddenly came out from Rach Gam and Xoai Mut to block both ends of the enemy’s formation and herd the enemy into a prepared encirclement. At the same time, Tay Son’s cannons from both river banks and the islet of Thoi Son threw shells at the middle of the enemy’s fleet which was getting stuck. Being blocked at both ends and overwhelmed by Tay Son’s troops from the beginning, the enemy’s troops and warships were panicked and chaotic. While being attacked by continuous artillery fire from Tay Son’s Army, Siam-Nguyen’s troops had to devote efforts to resisting a series of attacks by Tay Son’s warships in ambush directly aimed at the flanks of the enemy’s fleet, which was getting stuck, and Tay Son’s naval reinforcements from My Tho. Under Nguyen Hue’s command, Tay Son’s troops went into the decisive fight with a courageous spirit. Tay Son’s naval and infantry troops cooperated with one another in tightening the encirclement, step by step destroying all sections of the enemy’s troops, pushing the enemy’s warships into a desperate situation, laying siege to the enemy at the campaign level, and dividing their formation tactically, thereby panicking the enemy’s troops. A series of the enemy’s warships were sunk while a countless number of the enemy’s troops were shot, killed, and drowned in the river. A small number of the enemy’s troops tried to swim to shore, but they were annihilated by Tay Son’s infantry force. About three thousand or four thousand Nguyen Anh’s troops were no better than Siam’s troops and completely disintegrated. Nguyen’s generals all fled for their life. Siam’s infantry troops in Tra Tan also dementedly fled back to their country after Tay Son’s Army had destroyed Siam’s naval force in Rach Gam and Xoai Mut. According to the study by historian Nguyen Luong Bich, after the battle of Rach Gam - Xoai Mut, right on January 19th 1785, Tay Son’s Army was able to attack Siam’s troops in Tra Tan.
Siam’s large-scale military invasion was smashed by Tay Son’s Army under Nguyen Hue’s excellent command, with only a battle. The victory of the battle of Rach Gam - Xoai Mut shows us Nguyen Hue’s talent as a military genius, from his selection of combat method and theatre of war to his adoption of measures for dragging the enemy out of their base and annihilating them, which could be seen as the features of Vietnamese military art. The valuable lessons drawn from this battle should continue to be further studied, inherited, and creatively developed in today’s Homeland protection.
Sr. Col. Nguyen The Vy, MA
The Political Academy