The Siamese conquest of Lan Na (1774–1775) was a military conflict between the Konbaung dynasty of Burma (now Myanmar) and the Thonburi Kingdom of Siam (now Thailand).
After about two hundred years of Lan Na kingdom under Burmese rule, the Siamese armies under King Taksin of Thonburi led an expedition to the northern city of Chiang Mai. The Siamese managed to take Burmese-held Chiang Mai in January 1775 and began the transfer of Lan Na from Burmese rule to Siamese domination.
Background
Lanna under Burmese rule After the Burmese king Bayinnaung of the Toungoo dynasty conquered Chiang Mai in 1558, Lanna Kingdom (modern Northern Thailand) had been under Burmese rule for about 200 years. In 1723, Inthasom usurped the throne from King Ong Kham of Lao Luang Phrabang Kingdom. Ong Kham, the Lao prince who was of Tai Lue origin, sought political refuge in Chiang Mai where he became a Buddhist monk. In 1727, a native Lanna man named Thepsingh arose against the Burmese rule and killed the Burmese Myowun or governor of Chiang Mai. The Burmese in Chiang Mai sought help from Ong Kham who had been a monk. Ong Kham led the Burmese to successfully oust Thepsing from Chiang Mai. However, the Burmese refused to accept Ong Kham as king so Ong Kham turned against the Burmese and expelled their attacks. Ong Kham, the Tai Lue prince from Luang Phrabang, declared himself King of Chiang Mai in 1727 as an independent sovereign.
In the early eighteenth century, the weakening influence of the Burmese Toungoo dynasty allowed Lanna to exert some independence. However, Lanna fragmented into distinct city-states of Chiang Mai, Lampang, Lamphun, Phrae and Nan, each with its own independent rulers. King Alaungpaya of the new Burmese Konbaung dynasty rose to power in Burma and conquered the Mon Kingdom of Hanthawaddy in 1757. In 1757, Lanna rulers of Chiang Saen, Chiang Tung, Chiang Khong, Phrae and Nan, practically most of the petty Lanna rulers, sent congratulatory tributes to Alaungpaya at Pegu or Hanthawaddy, submitting themselves to the Burmese domination under the new dynasty. However, Chiang Mai remained defiant, not sending tributes nor submitting. Chiang Mai had to be taken by force and Burma was yet to assume actual control over Lanna. Alaungpaya still had to declare his intention to conquer Chiang Mai in 1759 because Chiang Mai was not yet under his control.
Ong Kham ruled Chiang Mai peacefully for thirty-two years until his death in 1759 and was succeeded by his son Ong Chan. However, Ong Chan was deposed by his younger brother who gave the throne to another Buddhist monk, Khihut in 1761. In 1762, King Naungdawgyi, son and successor of Alaungpaya, sent his general Abaya Kamani to lead the army of 7,000 men to invade Chiang Mai. The Burmese laid siege on Chiang Mai for seven months until Chiang Mai fell to the Burmese in August 1763. The former king Ong Chan and nearly the whole populace of Chiang Mai were deported to Burma. King Hsinbyushin appointed Abaya Kamani as the Burmese governor of Chiang Mai. Therefore, Chiang Mai came under Burmese rule again. The Burmese then used Lanna as the base to invade Ayutthaya from the north, leading to the Fall of Ayutthaya in 1767.
An animal hunter named Thipchang was declared as the local ruler of Lampang in 1732 with the title of Phaya Sulawaluechai. Thipchang ruled Lampang until his demise in 1759. Another pretender took the city of Lampang, prompting Thipchang's son Chaikaew to seek support from the Burmese court of Ava. The Burmese took Lampang in 1764 and installed Chaikaew as the ruler of Lampang under Burmese suzerainty. Abaya Kamani, the Burmese governor of Chiang Mai, died in 1769. He was succeeded by Thado Mindin (, known in Thai sources as Po Myowun , ) as Burmese governor of Chiang Mai. Thado Mindin pursued assimilation policies on Lanna and reduced the power of local native Lanna nobles. Thado Mindin held Chaikaew as political hostage in Chiang Mai, leaving Chaikaew's son Kawila to oversee the affairs in Lampang on behalf of his father.
Siamese expedition to Chiang Mai (1771) King Taksin defeated the last rival regime of Sawangkhaburi in 1770 and gained control of Hua Mueang Nuea or Northern Siam. In 1771, Thado Mindin marched Burmese forces from Chiang Mai to attack and lay siege on Sawankhalok. Chaophraya Phichairacha the governor of Sawankhalok, Chaophraya Surasi the governor of Phitsanulok and Phraya Phichai the governor of Phichai defeated the Burmese at Sawankhalok as Thado Mindin retreated.
In retaliation, King Taksin initiated his expedition to attack the Burmese-held Chiang Mai in March 1771. He assembled his armies of 15,000 men at Phichai, where Mangchai the ruler of Phrae submitted. Taksin sent Chaophraya Surasi ahead as vanguard with himself marched through Sawankhalok, Thoen and Li to reach Lamphun. Thado Mindin relinquished the earthen outer wall of Chiang Mai and took defensive position on the inner wall. Surasi and the Siamese took position on the outer wall. The Siamese attacked Chiang Mai but were unable to take the city. King Taksin then listened to a prophecy that any Siamese monarch who wished to take Chiang Mai would fail on first attempt and succeed on second attempt. After the nine-day siege, Taksin commanded his troops to retreat and ended the campaign.
However, upon seeing the Siamese retreat, Thado Mindin ordered the Burmese troops to counter-attack. The Burmese attacked the Siamese rearguard so heavily that it dissipated and the Burmese reached the main royal army. King Taksin himself took up arms and personally fought the Burmese with his sword. Taksin recovered the morale of Siamese armies as they managed to defeat and repel the pursuing Burmese.
Conflict between Thado Mindin and Phaya Chaban
Thado Mindin the Burmese governor of Chiang Mai sought to reduce the power of local Lanna nobility. In 1770, he ordered that all Lanna men should tattoo their thighs and all Lanna women should pierce their ears in accordance with Burmese customs. Phaya Chaban (, personal name Boonma), Kawila and other Chiang Mai nobles petitioned to King Hsinbyushin that Thado Mindin had abused his powers. Hsinbyushin ruled that the traditional rights and powers of native Lanna nobles should be respected. However, Thado Mindin refused to accept the Burmese king's ruling and sent his force to arrest Phaya Chaban. Phaya Chaban also fought with his own army, resulting in a civil war in Chiang Mai in November 1771. Thado Mindin prevailed with numerical superior forces. Phaya Chaban fled Chiang Mai and sought refuge with Nemyo Thihapate the Burmese general at Luang Phrabang.
In 1773, King Ong Bun of Vientiane, who was then a vassal of Burma, informed King Hsinbyushin that, despite the Fall of Ayutthaya and the total destruction of the Siamese Kingdom in 1767, Siam had recovered and consolidated under the leadership of Phraya Tak or King Taksin. Hsinbyushin ordered Nemyo Thihapate to gather troops at Chiang Mai to invade the Thonburi Kingdom from the north. Nemyo Thihapate was responsible for Burmese military activities in Lanna and was not on good terms with Thado Mindin. Thado Mindin requested Nemyo Thihapate to hand over Phaya Chaban but Nemyo Thihapate refused.
Burmese attacks on Phichai
As Nemyo Thihapate finished his campaigns in Luang Phrabang in 1772, he sent an army to attack the northern Siamese border town of Phichai. Phraya Phichai defended his city and Chaophraya Surasi repelled the Burmese invaders. The Burmese attacked Phichai again in 1773, personally led by Nemyo Thihapate. Surasi and Phichai confronted the Burmese to the north of the town of Phichai in January 1774. Phraya Phichai took up his swords in two hands and fought the Burmese. His swords broke in battle, earning him the epithet Phraya Phichai Dap Hak () or Phraya Phichai of the Broken Sword.
Mon Rebellion of 1774 In 1774, King Hsinbyushin of Burma ordered Mingyi Kamani Sanda the governor of Martaban to organize armies to invade Siam from the west through the Three Pagodas Pass. Mingyi Kamani Sanda commanded the Mon regiment under Binnya Sein to lead the vanguard into Siam first. However, as the Mon leaders had left Martaban, Mingyi Kamani Sanda forcibly extorted money from the Mon families of Martaban to raise money for the campaigns. Binnya Sein and other Mon leaders, upon learning of Burmese mistreatments of their families back in Martaban, rebelled against the Burmese and returned to take Martaban. Binnya Sein marched his Mon armies to take Yangon but was repelled by the Burmese. The Mon insurrection was defeated and Binnya Sein took refuge in Siam. This incident led to mass migration of Mon people from Martaban into Siam through the Mae Lamao and Three Pagodas Passes.
Siamese expedition to Chiang Mai (1774-1775) King Taksin of Thonburi decided to renew an expedition to Chiang Mai in 1774 due to the fact that the Burmese of Northern Lanna had harassed several Siamese border towns including Phichai and Sawankhalok. Thonburi court also heard of Hsinbyushin's grand plan to invade Siam from both northern and western directions. Taksin then conducted the pre-emptive strike on the Burmese at Chiang Mai as follows;
20,000 men from Hua Mueang Nuea or Northern Siamese towns were levied and gathered at Tak. 15,000 men from Thonburi were assembled to join the royal forces
King Taksin marched his Thonburi royal fleet and left the city in November 1774. The fleet went riverine upstream, reaching Kamphangphet and Tak. From Tak, Taksin ordered Chaophraya Chakri, Chaophraya Surasi and Chaophraya Phichairacha to lead the vanguard to Thoen. At Thoen, Thao Chomphou a local Lanna noble killed the Burmese governor there and submitted to the Siamese.
Thado Mindin reported to the Burmese court that the two Lanna nobles Phaya Chaban and Kawila were suspected to be involved in sedition. The Burmese court then summoned the two Lanna nobles to Ava. However, Nemyo Thihapate protected Phaya Chaban and Kawila, refusing to let Thado Mindin arrest those two Lanna men. This led to conflict between Thado Mindin and Nemyo Thihapate.
Phaya Chaban, upon learning of Siamese upcoming expedition to Chiang Mai, decided to seek Siamese support. Phaya Chaban sent a secret message to Kawila at Lampang, urging him to join his uprising. Kawila complied. Phaya Chaban then devised his plan and volunteered himself to Nemyo Thihapate as vanguard against the Siamese. Nemyo Thihapate allowed Phaya Chaban to lead the group of 70 Burmese men and 50 Lanna men ahead downstream of Ping River to clear the waterways of sediments and obstructions. Phaya Chaban marched his retinue down south to Hot where he massacred all the 70 Burmese and ran to submit himself to Chaophraya Chakri at Thoen. Chaophraya Chakri then sent Phaya Chaban to meet King Taksin at Tak.
At Lampang, Kawila organized a plan to overthrow the Burmese. Kawila sent his younger brother Khamsom to lead an army to the south pretending to fight the Siamese. Kawila then arose and killed the Burmese officials. The Burmese went to Khamsom. Khamsom told the Burmese that Kawila was acting on his own and this rebellion did not involve his family as a whole. The Burmese, however, were not convinced and reported the incidents to Thado Mindin at Chiang Mai. Thado Mindin realized that Kawila and his family were insurrecting against the Burmese rule. He had their father Chaikaew in Chiang Mai imprisoned. Khamsom sent a message to Thado Mindin, pleading that his father was not involved and Kawila was acting alone. Thado Mindin asserted that further investigations will determine their loyalty.