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 the lands in the
rainy season were swampy and ravaged with disease, making it unsuitable for marching and encampment. King Bodawpaya ordered the Burmese forces at
Tavoy to retreat to Martaban under the command of Minhla Sithu, 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 and returned to
Ava. The Burmese armies stationed at Martaban 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 Min Uparaja) to Martaban to organize the new invasion of Siam.
Preparations Prince Nanda Kyawdin or
Einshe Min Uparaja took the lead of the army of 50,000 men at
Martaban, with
Wundauk Nemyo Kyawzwa as his
Sitke. 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 Sithu, 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. After King
Rama I and Prince
Maha Sura Singhanat (the
Front Palace) received news of the Burmese advance, they ordered the mobilization of forces in
Bangkok and the provincial towns. In late February 1786, they departed Bangkok by river with the royal flotilla, accompanied by the vessels of senior nobles and officials in full formation. The vanguard was placed under Prince Maha Sura Singhanat and
Chao Phraya Rattanapiphit (acting
Samuhanayok), consisting of about 30,000 troops drawn from the
Grand Palace and the
Front Palace, and was sent ahead. The main royal army followed with the
Rear Palace and other princes, providing a further reinforcement of slightly over 30,000 men.
Phraya Phonlaphop was ordered to remain in Bangkok to oversee the defense of the capital. King Rama I subsequently led the royal army by river to Sai Yok, disembarked, and established his camp approximately 2.8 kilometers behind the Front Palace's army. He then ordered his commanders to deploy their forces and position themselves in close proximity to the Burmese army at Tha Din Daeng. On February 21, 1787, the Thai forces launched a simultaneous attack on the Burmese positions at both Tha Din Daeng and Samsop. The battle raged day and night, characterized by heavy artillery exchanges. After approximately three days of fighting, on February 23, the Burmese forces were routed and forced to retreat. Upon learning of the defeat and retreat of his vanguards—commanded by the Myanwun and Myanmewun—the Burmese Crown Prince ordered his main army to fall back to
Martaban. The Thai forces pursued the retreating troops, inflicting heavy casualties, and advanced as far as the Mae Kasat River, the site of the Crown Prince's encampment. King Rama I then ordered the complete destruction of the Burmese granaries and supply depots before leading his army back to the capital. ==Aftermath==