Siamese–Cambodian War (1591–1594)

The first campaign against Cambodia was launched in 1591, when the Siamese under general Phra Ratcha Manoo invaded through the Phra Charuk passage. Cambodian king Satha dispatched armies to Pursat and Battambang while also preparing an ambush in the Ranam forest. Despite initial success, the Cambodians were eventually driven out of Ranam after Thai reinforcements launched a second assault on the position. Pursat and Battambang soon fell into Thai hands, while the Longvek citadel became besieged. The siege lasted for three months, after which a combination of logistical issues and Cambodian counterattacks forced the Thais to retreat beyond the border.[12]

After warding off another Burmese invasion in 1593, Naresuan divided his army into four columns in preparation for another assault on Cambodia. The first column assembled in Nakhon Ratchasima, while aiming to attack Siem Reap and Kampong Svay. The second column was to amass recruits from the south of Ayutthaya and then march on Moat Chruk (present-day Long Xuyen). The third army moved on Banteay Meas, while the fourth army once more targeted Pursat and Battanbang. The four armies would then be able to simultaneously strike the already surrounded Longvek. The Cambodians had in turn assembled a force of 75,000 men and 150 junks that occupied key positions in Babaur, Battambang, Pursat, Banteay Meas, and Phnom Penh. Siamese scouts managed to detain a number of Cambodian soldiers who upon interrogation revealed the positions of their comrades. The newly-acquired information facilitated the fall of Battambang.[13][14]

A second battle fought in front of Pursat ended in defeat for the Cambodians, who were outflanked during the course of the battle. Three days later, the Siamese forces reached Babaur and began digging trenches around the city. By dusk Siamese sappers had mined their way up to the city's walls, thus initiating hand-to-hand combat. Cambodian prince Soryopor managed to fight his way out of the encirclement with 1,000 men while the rest of the defenders perished in the fighting. After reaching Lovek, Soryopor assumed direct command of the defenses as his brother Chey Chettha had by that time abandoned the city. Assisted by Spanish and Portuguese mercenaries Soryopor reinforced the walls with cannons and spikes, while also requesting assistance from Vietnam and the Spanish governor of Manila.[15][16]

In the meantime the Cambodian navy was overpowered outside Moat Chruk, as the Siamese armies slowly converged on Longvek. Siamese engineers began the siege by erecting earthworks that surpassed the city's fortifications in height, thus enabling them to fire directly at the city. The Cambodians responded by building a second wall that shielded the city from bombardment. On 3 January 1594, following an hour long artillery preparation, Naresuan's army stormed the city. Siamese war elephants went on to break the city gates, allowing the infantry to penetrate the inner walls and slay the remnants of the garrison. Although King Satha managed to escape into neighboring Laos, 90,000 Cambodians, including Prince Soryopor, were taken to Ayutthaya.[2]