The Burmese–Siamese War (1759–1760) (; ) or Alaungpaya's War () 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.
Background
Summary of Burmese–Mon–Siamese conflicts
Burmese King Tabinshweti of Toungoo dynasty conquered the Mon Kingdom of Hanthawaddy in Lower Burma in 1539. However, the Mons soon rebelled and had to be reconquered by King Bayinnaung in 1551. Burmese kings of Toungoo dynasty established their royal capital at Pegu or Hanthawaddy, which had been the Mon royal seat, respecting Mon culture. In 1555, Bayinnaung conquered the Shan-occupied Ava and Upper Burma, uniting Burma under a single rule for the first time since the Pagan kingdom. Bayinnaung went on to conquer Lanna Chiang Mai (1558), Manipur (1560) and Tavoy (1562). In 1563, King Bayinnaung led his Burmese armies to invade neighboring Siamese Kingdom of Ayutthaya. King Thammaracha of Phitsanulok, a Siamese vassal king, allied with the Burmese king. Bayinnaung then went on to lay siege on Ayutthaya, resulting in the surrender of Ayutthaya in 1564. However, conflicts between Ayutthaya and Burmese-backed Phitsanulok prompted Bayinnaung to send another invasion force to attack Ayutthaya. Ayutthaya fell to Burmese invaders in 1569. Bayinnaung appointed Thammaracha as King of Ayutthaya and his vassal. During his reign, Burmese king Bayinnaung expanded his kingdom to unprecedented territorial size and influence. Bayinnaung appointed his own son, Nawrahta Minsaw, to be King of Chiang Mai and ruler over Lanna.
Bayinnaung died in 1581, leaving the throne to his son Nanda Bayin. Burma then entered a period of decline. Naresuan broke his Siam kingdom free from Burmese domination in 1584. In 1586, Nanda Bayin himself marched Burmese forces to attack and lay siege on Ayutthaya in retaliation but failed to reconquer Ayutthaya. After 1587, Burmese forces would not reach Ayutthayan outskirts again for the next two hundred years (until 1760). In 1592, Nanda Bayin sent his son the crown prince Mingyi Swa to invade Siam. Naresuan intercepted the Burmese at Western frontiers near Suphanburi, leading to the Battle of Nong Sarai in 1593, in which Naresuan prevailed over Burmese invaders and the Burmese crown prince was killed in battle. After the victory, Siam went on offensives, reclaiming Tavoy and Tenasserim in 1593 and taking control of Martaban in 1594. Burma disintegrated into competing princely regimes of Ava, Prome and Toungoo. Even King Nawrahta Minsaw of Chiang Mai submitted to Naresuan, bringing Lanna under Ayutthayan domination. The Burmese Prince of Toungoo, in collaboration with Arakan Kingdom, successfully seized Pegu the Burmese capital in 1599. Naresuan embarked on his grand campaign to invade Lower Burma in 1600. Prince of Toungoo brought Burmese king Nanda Bayin to his hometown at Toungoo, leaving the Arakanese to freely plunder and burn down Pegu. Naresuan followed to Toungoo, laying siege on the city but did not succeed and turned back. Nanda Bayin the Burmese king himself was assassinated in 1600 by Nat Shin Naung, son of the Toungoo prince.
After the death of Nanda Bayin, Burma descended into civil war with regional regimes sprang up at Ava, Prome, Toungoo and Syriam. In 1603, Prince Nyaungyan of Ava attacked Shan States, which were allies of Siam. Naresuan led Siamese armies to support the Shans but died on his way in 1605. Nyaungyan also died in 1605 during his Shan campaign, succeeded by his son Anaukpetlun. From Ava, Anaukpetlun conquered all of his rival regional regimes, uniting Burma again under his rule. In 1613, Anaukpetlun reestablished Pegu as Burmese royal capital. The new Burmese king also reconquered Martaban, Tavoy (1614) and Chiang Mai (1615) from Siam. After this, Burmese–Siamese conflicts cooled down and reached stalemate, with Burma being in control of Lanna, Martaban and Tavoy and Siam controlling Tenasserim. King Thalun moved Burmese capital from Pegu in Lower Burma to Ava in Upper Burma in 1636, The Mons of Lower Burma were then neglected by the Burmese court, allowing them to be more autonomous. In 1660, Qing China invaded Burma in search for Southern Ming Yongli Emperor who had taken refuge in Burma. The panicked Lanna King of Chiang Mai requested aid from King Narai of Ayutthaya. Burma conscripted Mon people to fight Chinese invaders, leading to Mon rebellion at Martaban in 1661. King Narai led Siamese forces north to Lanna but the Chiang Mai king annulled this alliance as the war turned to Burmese favor. Burmese king Pindale sent Burmese armies to subjugate the Mon rebellion, proceeding to invade Western Siam through the Three Pagodas Pass. The Siamese repelled Burmese invaders in 1661 at Saiyok near Kanchanaburi. King Narai conquered Chiang Mai in late 1661. Siam retaliated by attacking Tavoy up to Martaban on Tenasserim Coast in 1662. However, Siam did not seek to permanently occupy Lanna and the Mon lands so these Siamese conquests reverted back to Burmese rule.
Decline and Fall of Toungoo dynasty