Burmese–Siamese War of 1759–60

The Burmese–Siamese War (1759–1760) (Burmese: ယိုးဒယား-မြန်မာစစ် (၁၇၅၉–၁၇၆၀); Thai: สงครามพม่า-สยาม (พ.ศ. 2302–2303)) or Alaungpaya's War (Thai: สงครามพระเจ้าอลองพญา) was the military conflict between the Konbaung dynasty of Burma (Myanmar) and the Ban Phlu Luang Dynasty of the Ayutthaya Kingdom of Siam, in which the Burmese forces under King Alaungpaya of the Konbaung dynasty invaded Siam. After about a century of relative hiatus of Burmese–Siamese conflicts, this war reignited the new round of military conflicts between Burma and Siam that would last for about a century to come.

After the fall of Burmese Toungoo dynasty at the hands of the Mons of Hanthawaddy in 1752, the Burmese resurged powerful under King Alaungpaya who founded the new Konbaung dynasty in 1752. In the course of Burmese reunification, Burmese forces under charismatic leadership of Alaungpaya had gained military experiences, including expulsion of the British and the French from Lower Burma. Burma reconstituted into a militarized polity, whereas Siam, centered on Ayutthaya, had not faced any serious external threats or military conflicts since late seventeenth century and Siamese defense system had been largely in disuse. Siam, through the eighteenth century, had been plagued with internal rebellions, succession disputes and decline of manpower control. Chronic manpower shortage undermined Siamese defense system.

Immediate causes of the war were dispute over the Tenasserim Coast and perceived Siamese support to the Mons of Lower Burma in their insurgency against Burmese rule. King Alaungpaya was provoked by the incident in which Burmese royal ship was seized by the Siamese in September 1759. Siamese authorities at Mergui refused to repatriate a Mon rebel ship, branded as a royal Burmese ship, to Burma. This Burmese military expedition was also driven by the Indic Chakravarti or Cakkavatti ideology, in which Alaungpaya viewed himself as Universal Ruler with boundless military conquests with the goal to bring forth the new epoch of Bodhisattava or Future Buddha.

Alaungpaya and his Burmese forces of 40,000 men left Rangoon to invade Siam in late December 1759, with his second son Prince Thiri Damayaza of Myedu (later King Hsinbyushin) and his childhood friend Minkhaung Nawrahta as vanguard commanders. Going through Martaban, the Burmese vanguard conquered Tavoy in December. After taking the whole Tenasserim Coast, Alaungpaya and his Burmese forces entered Siam crossing the Tenasserim Hills through the Singkhon Pass in early March 1760. The news of Burmese invasion came as a surprise for Ayutthaya, who was unprepared, panicked and disorganized. King Ekkathat sent his inexperienced Siamese forces to face the Burmese at Singkhon Pass, resulting in the Burmese prevail, humiliating Siamese retreat and the desperate heroic stand of Khun Rong Palat Chu well-narrated in Thai nationalistic history.

Ayutthaya adopted the traditional strategy of passive stand inside of Ayutthaya citadel against the invaders, relying on formidable wall of Ayutthaya and arrival of rainy wet season to ward off the invaders. The Burmese swept through Western Siamese towns of Kuiburi, Phetchaburi, Ratchaburi and Suphanburi. The more-capable temple king Uthumphon, who had previously abdicated in 1758 to become a monk, returned to power to assume military commands. In the Battle of Talan or Noi River in late March 1760, impulsivity of Prince Myedu nearly resulted in Burmese defeat as the Siamese fired onto the river-crossing Burmese but timely arrival of Alaungpaya's main forces saved the situation. Siamese commander and Minister of Military, Chaophraya Kalahom Khlongklaeb, was killed in battle.

The Burmese eventually reached the outskirts of Ayutthaya in late March 1760. Alaungpaya took position at Ban Kum or Bangban to the northwest of Ayutthaya, while his vanguard under Minkhaung Nawrahta approached the northern walls of Ayutthaya to attack. The Siamese adhered to the passive defense strategy, convinced that the Burmese were obliged to leave at the advent of rainy season. The Burmese attacked Ayutthaya in April 1760, resulting in gruesome massacre of Ayutthayan people and foreign merchants on the southern moat. Minkhaung Nawrahta fires cannons into the Ayutthaya citadel, damaging structures including Ekkathat's royal residence.

Alaungpaya the Burmese king fell ill in mid-April 1760. His son Prince Myedu and his friend Minkhaung Nawrahta convinced Alaungpaya to retreat. Alaungpaya and his Burmese forces retreated in April 1760, leaving Minkhaung Nawrahta at Ban Kum as rearguard against any possible Siamese pursuits, utterly destroying Siamese pursuing forces. Ayutthaya was thus saved from Burmese conquest as the passive defense strategy worked for one last time, postponing the fall of Ayutthaya for seven years. After a long journey, going back to Burma through the Maesot Pass, the ailing King Alaungpaya died in May 1760 at a place near Martaban, ending the life of an impactful man who, in the course of his eight-year-reign, reunified Burma under his new powerful militaristic regime, sparking a chain of events that would profoundly affect the history of Continental Southeast Asia.

This war laid foundation for the next Burmese invasion of Siam in 1765–1767. The Burmese, particularly Prince Myedu, learned about Siamese strategy and tactics. The death of Alaungpaya was followed by a new round of internal unrests in Burma, including the rebellion of Minkhaung Nawrahta himself in 1760. The new Burmese king Naungdawgyi pacified the unrest by 1762 but died prematurely next year in late 1763. Prince Myedu, son of Alaungpaya and younger brother of Naungdawgyi, eventually ascended the Burmese throne as King Hsinbyushin in 1763. Hsinbyushin viewed the conquest of Ayutthaya as due accomplishment unattained by his father Alaungpaya so he was determined to finish the mission. Hsinbyushin innovated and conveyed his new strategy to his commanders sent into Siam in 1765, effectively circumventing and undoing traditional Siamese defense strategy, leading to the eventual destructive fall of Ayutthaya in 1767.