Burmese preparations

King Bodawpaya began his Siamese expeditions in July 1785.^[5] The Burmese forces were drafted from its various tributary states, most notably the northern Shan states of Hsenwi, Mongnai, Kengtung, Banmaw, Mongkawng and Hsipaw.^[5] Bodawpaya first sent Mingyi Mingaung Kyaw to lead an army of 10,000 men to Martaban to arrange the provisions and supplies for the massive royal army and for the fleets at Mergui. However, supply shortage and line communications were the main issue for the Burmese armies. The Burmese were unable to quickly move the large number of men and provisions in time.^[5]

King Bodawpaya and his armies left Ava on November 11, 1785. When the king arrived at Martaban on December 20, he found that the supplies did not meet the demands. He ordered Mingyi Mingaung Kyaw arrested from Mergui to be brought to him in chains. After waiting for four days at Martaban, King Bodawpaya was furious that the transportation of men, horses and elephants across the Salween River was delayed and had not been completed. He struck a spear at one of his generals, wounding him. Only with the beseeching of the governor of Kawthanti that the royal temper was cooled down. After staying in Martaban for a month, King Bodawpaya and his royal forces left Martaban on January 19, 1786, towards the Three Pagodas Pass.^[5]

Siamese preparations

In November 1785, three Burmese men were captured by the Karens of Kyaukkaung.^[5] The captured Burmese revealed to Siamese authorities that King Bodawpaya was planning a massive invasion of Siam in multiple directions. King Rama I convened a council of royal princes and ministers to discuss the situation. The Siamese then sent a Burmese man named Nga Gan,^[5] who was a former retainer of King Bodawpaya captured by the Siamese, to negotiate with King Bodawpaya at the Three Pagodas. King Bodawpaya, however, was not interested in peace-making and instead inquired Nga Gan about Siamese preparations. The Bangkok court then sent warnings to various cities in Northern and Southern Siam about the impending invasions.

Prelude

Due to a lack of supplies, Bodawpaya couldn't commit all his forces, numbering 88,000 men, present at the Kanchanaburi front. He was only able to send the 4th Division with 10,000 men under Minhla Kyawdin and the 5th Division with 5,000 men under Mingyi Maha Mingaung.

Prince Maha Sura Singhanat with 30,000 men marched from Bangkok in December 1785 along with his generals and retinue, reaching Lat Ya (Thai: ลาดหญ้า) (called Kanpuri in Burmese) in Kanchanaburi. He sent the Mon general Phraya Mahayotha or Binnya Sein to intercept the Burmese at Kram Chang (in modern Si Sawat District).

The vanguard Burmese armies of Minhla Kyawdin and Mingyi Maha Mingaung, numbered 15,000 combined, marched through Sai Yok and crossed from Khwae Noi River to Khwae Yai River, meeting Binnya Sein at Si Sawat. Binnya Sein was defeated and the Burmese continued to Latya at the foothills of Khao Chon Kai. They later set up camps. The Siamese army soon arrived and the Battle of Latya ensued.

Battle of Thung Lat Ya

Maha Sura Singhanat sent a Siamese army to attack the Burmese, but the Burmese were able to repel the Siamese attack. Both sides started building towers to place cannons on top to bomb each other. Both sides suffered heavy losses. To dissuade the Siamese soldiers from retreating, Maha Sura Singhanat built 3 large mortars and announce that if anyone retreats, they will be crushed by them.

Prince Maha Sura Singhanat noticed the Burmese supply lines were thin so he sent 500 men under the command of Phraya Siharatdecho, Phraya Tai Nam, and Phraya Phetchaburi to go ambush the Burmese supply lines at Phu Krai Sub-district. These men were too afraid to attack the Burmese army so they hid. They were later caught and beheaded. Maha Sura Singhanat then sent a force of 1,500 men under Khun Noen to ambush the Burmese supply lines. This devastated the Burmese supply lines.

A stalemate

The battle reached stalemate and was dragged on to January 1786. Being afraid that his brother would lose the engagement, King Rama I decided to march his 20,000-men army from Bangkok in January 1786 to support Maha Sura Singhanat Lat Ya, but the prince then convinced the king to return to Bangkok because he was confident of winning the engagement.

Breaking the stalemate

The Burmese side, upon observing the royal army arriving from Bangkok, believed that the Siamese was being reinforced. Prince Maha Sura Singhanat then had his army secretly march out of Lat Ya at night and march into Lat Ya again in the day, tricking the Burmese into believing that the Siamese was reinforced. With supply lines disrupted, the Burmese at Lat Ya were starved and deprived of morale. The Burmese killed horses for meat and dug for plant roots to eat. On 18 February 1786, the Siamese staged the all-out attack against the Burmese lines. Minhla Kyawdin and Mingyi Maha Mingaung the Burmese generals, unable to withstand Siamese attacks anymore, retreat. King Bodawpaya decided to give up the campaigns and ordered the general retreat of the Burmese armies on February 21, 1786.^[5]

Aftermath

After two months of battle, the Siamese were able to repel the Burmese invasion at Lat Ya. Prince Maha Sura Singhanat ordered the Siamese to follow the retreating Burmese as far as Sangkhlaburi where the armies of the two Burmese princes were stationed. Prince Thiri Damayaza and Prince Thado Minsaw reported to King Bodawpaya at Ranti River about the defeat. King Bodawpaya then ordered the general retreat. A large number of Burmese were captured as prisoners. Thai sources mentioned that the Burmese suffered around 6,000 casualties as a result of the battle.^[8]

Prelude

Nemyo Nawratha divided his 10,000-men army into 3 groups. Nemyo Nawratha himself led an army of 4,000 men through the Bong Ti Pass (in modern Sai Yok District, Kanchanaburi Province) and stationed at Chom Bueng. Nemyo Nawratha also sent his subordinate Dawei Wun to lead an army of 3,000 men to enter Ratchaburi through Suan Phueng. Dawei Wun and his army stayed at Khao Ngu, just five kilometers to the northwest of the town of Ratchaburi itself. They sustained themselves by harvesting coconuts and other fruits in the region. The remaining 3,000 troops were sent to join the 1st Division under Maha Thiri Thihathu at Myeik. Chao Phraya Thamma Boonrot, who led the Siamese army of 5,000 men in Ratchaburi town, was still unaware of these Burmese advances.

Battle of Khao Ngu

After defeating the Burmese at Lat Ya in February 1786, Prince Maha Sura Singhanat then marched to Ratchaburi. He sent his two generals Phraya Kalahom Ratchasena and Phraya Chasaenyakorn ahead as vanguard. The two generals met the Burmese at Khao Ngu and defeated Dawei Wun and the Burmese army in the Battle of Khao Ngu. Dawei Wun retreated towards Suan Phueng and was followed by the Siamese. Nemyo Nawratha at Chom Bueng, upon seeing the defeat of Dawei Wun at Khao Ngu, also decided to retreat as soon as he had received orders from King Bodawpaya.

Aftermath

Prince Maha Sura Singhanat was angry that the Siamese general Chao Phraya Thamma Boonrot had allowed the Burmese to penetrate so deep into Ratchaburi. The prince petitioned King Rama I for Thamma Boonrot to be executed. However, as Thamma Boonrot had been a supporter in his ascension, King Rama I ordered his life to be spared. Thamma Boonrot was then whipped and paraded through the camps in shame with his head shaved. He was also stripped of his title and position as the Minister of Palatial Affairs.

Siege of Lampang

Prince Thado Thiri Maha Uzana ventured to recruit men from the Shan States and marched the Burmese army of 30,000 men to Chiang Saen. The Burmese governor of Chiang Saen called Aprakamani also provided resources. As Chiang Mai had been abandoned since 1776, the main outpost of the Lanna Kingdom against the Burmese was Lampang. Prince Thado Thiri Maha Uzana and Aprakamani marched from Chiang Saen to attack Lampang in December 1785, leading to the siege of Lampang. Prince Kawila, the ruler of Lampang, defended the city.

Preludes to the Battle of Pakphing

Prince Thado Thiri Maha Uzana also sent his Sitke, Nemyo Sithu, to lead an army of 3,000 from Lampang down south towards the Upper Chao Phraya Plains. The governors of Sawankhalok, Sukhothai and Phitsanulok, due to manpower shortages, decided to abandon their cities and flee into the jungles as they were unable to raise armies against the Burmese. Nemyo Sithu marched through these cities unopposed and stationed his camps at Pakping, twenty kilometers to the south of the city of Phitsanulok. The 9th Division of Nawratha Kyawgaung also entered the Chao Phraya Plains from the west through Rahaeng or modern Tak. The governor of Tak surrendered and was captured to Burma.

Battle of Pakphing

Prince Anurak Devesh marched his army of 15,000 men from Bangkok to encamp at Nakhon Sawan. He sent Chao Phraya Mahasena Pli to Phichit just south of Pakphing to face Nemyo Sithu. The Siamese army of Prince Anurak Devesh in Upper Chao Phraya Plains was at risk of being attacked from two directions; from Pakphing by Nemyo Sithu in the north and from Tak by Nawratha Kyawgaung from the west. Prince Anurak Devesh ordered Phraya Phraklang Hon to stay at Chai Nat to defend the rear lines against possible Burmese attacks from Tak. However, as both the Burmese and Siamese took their positions, neither sides engaged.

Prince Maha Sura Singhanat and his generals returned from Ratchaburi to Bangkok in March 1786. King Rama I and Prince Maha Sura Singhanat devised the second-phase plan, in which King Rama I would lead armies to the north and Prince Maha Sura Singhanat to the south. King Rama I sent message to his nephew Prince Anurak Devesh at Nakhon Sawan, urging him to initiate the attacks against the Burmese. King Rama I marched the royal army of 30,000 men to Phichit to supervise campaigns in the northern theater, leaving Bangkok on March 10, 1786. As the king went to Phichit, Prince Anurak Devesh also moved to Phichit. King Rama I ordered another nephew Prince Thepharirak and Phraklang Hon at Chai Nat to march against Nawratha Kyawgaung at Tak. Prince Anurak Devesh and Mahasena Pli at Phichit eventually engaged with Nemyo Sithu at Pakphing, leading to the Battle of Pakphing on 18 March 1786. The Burmese were defeated and Nemyo Sithu withdrew westward. The Burmese fled to the west crossing the Nan River where they were massacred by the pursuing Siamese and the bodies filled the river.

Relieving the siege of Lampang

After the Battle of Pakping, King Rama I ordered Chao Phraya Mahasena Pli, together with the king's half younger brother Prince Chakchetsada, to lead the Siamese army to the north to relieve the siege of Lampang. When Prince Thepharirak sent Phraklang Hon had reached Kamphaeng Phet, however, Nawratha Kyawgaung at Tak retreated after the Burmese defeat at Pakping and the engagements did not occur. As both the Burmese of the north and west had retreated, the king and Prince Anurak Devesh returned to Bangkok.

Prince Kawila of Lampang had held out the town against the Burmese siege for four months. Mahasena Pli and Prince Chakchetsada reached Lampang in March 1786. The Siamese attacked the besieging Burmese at the rear and the Burmese Prince Thado Thiri Maha Uzana withdrew to Chiang Saen. Lampang was finally relieved from the Burmese siege. The Siamese was then able to repel the Burmese invasions in the Northern Theater.

Siege of Thalang

Prelude

Maha Thiri Thihathu sailed his 7,000-men fleet to disembark at Ranong, continuing to Kraburi and crossing the Tenasserim Hills at Pakchan to attack Chumphon. Maha Thiri Thihathu sent his Sitke-gyi Nemyo Gonnarat with 2,500 men ahead as vanguard. The governors of Chumphon and Chaiya decided to abandon their towns in the face of Burmese invasion due to manpower shortage. Maha Thiri Thihathu and Nemyo Gonnarat sacked both towns and continued southward to Nakhon Si Thammarat (Ligor). Chaophraya Nakhon Phat the governor of Nakhon Si Thammarat managed to raise an army of 1,000 men to march against the Burmese at the Tapi River in modern Phunphin District. Maha Thiri Thihathu, however, had a Siamese man from Chaiya to yell at the Ligorian army that Bangkok had already fallen to the Burmese. Chao Phraya Nakhon Phat was convinced that Bangkok had fallen because by then no reinforcements had arrived from Bangkok. Nakhon Phat decided to abandon the city of Ligor and, with his family, escaped to Khao Luang – a mountain to the west of Ligor. The inhabitants of Ligor also fled into the jungles as resistance against the Burmese collapsed. Maha Thiri Thihathu took Nakhon Si Thammarat with ease, plundering the city and enslaving the native Siamese.

After taking three consecutive towns on the coast of Gulf of Siam, Maha Thiri Thihathu headed for Phatthalung next. The inhabitants of Phatthalung, upon seeing the fate of their compatriots to the north, also fled the town. A local monk named Chuai^[10] encouraged the inhabitants of Phatthalung to fight against the Burmese. Chuai the monk managed to raise an army of 1,000 men and, with himself riding on a palanquin, marched against the Burmese at Cha-uat. However, the Burmese retreated before the engagements begun because the Bangkokian army was attacking from the north.

Battle of Chaiya

Prince Maha Sura Singhanat sailed his fleet of 20,000 men from Bangkok to the south, departing on March 4, 1786. The prince reached Chumphon and ordered his generals Phraya Kalahom Ratchasena and Phraya Chasaenyakorn to lead the vanguard to Chaiya. Maha Thiri Thihathu also sent Sitke-gyi Nemyo Gonnarat to Chaiya. Both sides engaged in the Battle of Chaiya. The Siamese was able to encircle the Burmese but the heavy rainfall neutralized most of the Siamese canons. Nemyo Gonnarat managed to break through the encirclement and fled westward and was closely pursued by the two Siamese generals. Many Burmese were captured as war prisoners and were brought to the prince at Chumphon. Burmese general Maha Thiri Thihathu at Ligor, upon seeing the defeat of his subordinate at Chaiya, decided to lead the Burmese to retreat westward through Krabi and back to Mergui. Prince Maha Sura Singhanat then marched to reclaim the city of Nakhon Si Thammarat.

Prince Maha Sura Singhanat ordered Chao Phraya Nakhon Phat to be brought to him for the crime of cowardice. However, Nakhon Phat was pardoned due to the inevitability of his situation and was assigned to restore the city. As the lasts of the Burmese were expelled from Southern Siam, the Nine Armies' War came to the end.

Prelude

After many defeats in early 1786, King Bodawpaya retreated to Martaban. However, he retained some of his forces on the Tenasserim Coast waiting for the new campaigns. The traditional wars were usually conducted in dry season as in the rainy seasons the lands were swampy and ravaged with diseases, unsuitable for marching and encampment. King Bodawpaya ordered the Burmese forces at Tavoy to retreat to Martaban under the command of Minhla Kyawdin, while Maha Thiri Thihathu was ordered to retreat from Mergui to Tavoy. The king then marched back to Dagon where he worshipped the famous Shwedagon Pagoda^[5] and returned to Ava. The Burmese armies stationed at Martanban and Tavoy, waiting for the rainy season to be over to conduct new invasions of Siam.

In September 1786, King Bodawpaya resumed his Siamese campaigns. He sent his eldest son and heir, Prince Thado Minsaw or Prince Nanda Kyawdin (known in Thai sources as Einshe Maha Uparaja) to Martaban to organize the new invasion of Siam.

Preparations

Prince Nanda Kyawdin or Einshe Uparaja took the lead of the army of 50,000 men at Martaban, with Wundauk Nemyo Kyawzwa as his Sitke and Mingyi Nanda Kyawdin as Bogyok.^[5] King Bodawpaya made sure that the provision shortage would not hinder the campaign again. He ordered the grain rations of Arakan and the whole Lower Burma to be sent to the frontlines. The Burmese also established strong supply lines with supply outposts stationed all along the way from Martaban to Kanchanaburi. Unlike the previous invasion, the Burmese concentrate the forces in single direction at Kanchanaburi instead of dispersing the forces in many directions. Prince Nanda Kyawdin sent Minhla Kyawdin, the Burmese veteran who had been defeated by the Siamese at the Battle of Latya seven months earlier, to lead the vanguard of 30,000 ahead into Kanchanaburi. The two Burmese vanguard commanders left Ava for Martaban on September 7, 1786.^[5]

Emboldened by their successes earlier in the year, the Siamese were much more confident in their responses to the Burmese invasion. Both King Rama I and his brother Prince Maha Sura Singhanat marched to meet the Burmese at Kanchanaburi.

• Prince Maha Sura Singhanat, along with his two generals Phraya Kalahom Ratchasena and Phraya Chasaenyakorn and Chao Phraya Rattanapipit the Samuha Nayok, marched ahead the army of 30,000 men.
• King Rama I himself and his nephew Prince Anurak Devesh of the Rear Palace led the royal army of 30,000 men.

The Siamese royal forces left Bangkok on February 1, 1787, for Kanchanaburi to the west to face the invading Burmese.

The Battle (February 1787)

The Burmese armies entered Kanchaburi through the Three Padodas Pass or Payathonzu. Minha Sithu divided his forces to station at Tha Dindaeng and Samsop, both in Sangkhlaburi, Kanchanaburi. Prince Nanda Kyawdin stayed at the Three Padogas. Prince Maha Sura Singhanat marched to Sai Yok in Kanchaburi and encamped. He ordered his generals Phraya Kalahom Ratchasena and Phraya Chasaenyakorn to march ahead as vanguard to Sangkhlaburi. When King Rama I had reached Sai Yok, Prince Maha Sura Singhanat moved to Sangkhlaburi. The Siamese armies concealed^[5] their movements in the jungles to stage the surprise attack on the Burmese.

After long marches, the two sides finally met at Tha Dindaeng and Samsop on 21 February 1787. The fighting lasted for two days until Minhla Kyawdin was quickly defeated, again for the second time, on February 23. This short war was called “Tha Din Daeng campaign”. Minhla Kyawdin retreated back to Payathonzu. Prince Nanda Kyawdin, upon seeing the defeat of Minhla Kyawdin, also retreated back to Martaban. The Siamese forces burnt all the Burmese grain supplies in Kanchanaburi

The campaign is commemorated by a park established by the Royal Thai Army 40 kilometres (25 mi) from the town of Kanchanaburi.^[11]

Aftermath

Despite the continuation of heated conflict between Burma and Siam in the next decades, including several Siamese attempts to recapture the Tenasserim Coast and a failed 1809 Burmese invasion to seize Thalang (renamed Phuket) Island and to contest Siamese control over the central peninsula, Bodawpaya's two failed invasions ultimately turned out to be the last two full-scale attempts by Burma to invade central Siam and to destroy Siam as a political entity.