Burmese–Siamese War was the major military conflict between the Konbaung Dynasty of Burma and Thonburi Kingdom of Siam. The Burmese invasion forces faced tough heavy resistance from the Siamese forces and finally withdrew the invasion when King Hsinbyushin died on June 10, 1776. As a result, the Burmese loss of southern Lan Na later proved to be the end of their 200 years rule.
Background
In 1774, after the peace concluded between Konbaung and Qing Dynasty, a rebellion flared up in Lan Na mainly due to the repressive rule of the Burmese governor there, Thado Mindin. His contemptuous treatment of the local chiefs earned him their indignation. When a Siam army under the command of Chao Phraya Chakri and Chao Phraya Surasi reached Lampang, Phraya Chaban, Phraya Vaiwongsa and Phraya Kawila, the three local chiefs who had deserted the Burmese joined him in laying siege to Chiang Mai and soon King Taksin arrived on the spot. The city fell to the Siam armies in January 1775. The Burmese king sent another small army of 5,000 to attack Siam. But it was completely surrounded by the Siamese at Battle of Bangkeo in Ratchaburi, and eventually starvation compelled the Burmese to capitulate to King Taksin. Taksin took them alive was to promote the morale of the Siamese people. The Burmese reinforcements who had encamped themselves in the province of Kanchanaburi were then mopped up. King Hsinbyushin, who had been in a long illness that would eventually take his life, now ordered Maha Thiha Thura, who known in Thai history as Azaewunky to lead a fresh invasion of Siam in October 1775.
Burmese preparations
The situation had changed a great deal since the last invasion of Siam ten years ago. King Hsinbyushin was dying, and the palace is full of rumors and intrigues. None of the Burmese commanders, including Maha Thiha Thura, were enthusiastic about the invasion. Maha Thiha Thura himself had a vested interest in the succession affairs as the heir-apparent Singu Min was his son-in-law. More importantly, the Burmese military commandbroke down. Dissension was rampant. Field commanders increasingly acted like warlords and behaved with arrogance towards the people, and began to ignore even the king's orders. Maha Thiha Thura faced many difficulties in raising an invasion force, and had to wait until the end of rainy season in 1775 to start the invasion.
Invasion
A combined force of 35,000 was eventually raised for the Siamese theater. Maha Thiha Thura's main army invaded by the southern route from Martaban, and Ne Myo Thihapate's army from Chiang Saen in northern Lan Na,. From the start, the invasion was fraught with multiple issues. First, the invasion force of 35,000 was too small to be effective whereas the 1765 invasion force consisted of at least 50,000 troops. More importantly, the Burmese command was in disarray. With the king on his deathbed, insubordination became increasingly rampant. Indeed, the second-in-command of the southern army, Zeya Kyaw, disagreed with Maha Thiha Thura on the invasion route, withdrew with his troops, leaving Maha Thiha Thura with a portion of the troops. Even with a full strength invasion force, an invasion of Siam was never easy for the Burmese. Without a full strength army, the effort appeared doomed from the start. Nonetheless, Maha Thiha Thura and Ne Myo Thihapate obeyed the orders, and marched on. Thihapate's army managed to recapture Chiang Mai, Maha Thiha Thura's army fought its way down to Siamese defenses and managed to occupy Phichai and Sukhothai provinces in northern Siam. In his interrogation of two Phichai officials, Maha Thiha Thura referred to Chao Phraya Surasih, the Governor of Phitsanulok, as "Phraya Sua" or "The Tiger", thus testifying to his boldness and decisiveness. The Burmese then besieged Phitsanulok which was defended by the brother generals, Chao Phya Chakri and Chao Phraya Surasi, and as the result of the stubborn resistance on the part of Siamese soldiers, they were checked outside the city ramparts for about 4 months. Hearing about Chao Phraya Chakri's counterattacks which drove back the Burmese to their well fortified camp, Maha Thiha Thura arranged a meeting with him, in the course of which he extolled his generalship and advised him to take good care of himself. He prophesied that General Chakri would certainly become king. If Maha Thiha Thura's purpose was to sow discord between King Taksin and Chao Phraya Chakri, he failed, as they collaborated closely in subsequent military expeditions. In spite of King Taksin's endeavour to attack the Burmese from the rear, Chao Phraya Chakri and Chao Phraya Surasi could not hold Phitsanulok any longer, due to lack of provisions. Having collected most of the inhabitants, they successfully fought their way through enemy lines and made Phetchabun their headquarters. Maha Thiha Thura led his army into the deserted city at the end of March 1776, but was soon confronted with the same problem of the shortage of food.
Retreat
By June, at the start of the rainy season, the Burmese armies were bogged down in central Siam by determined Siamese resistance led by king Taksin and Chao Phraya Chakri, the war was in a stalemate, and prospects of another conquest of Siam looked bleak. When King Hsinbyushin finally died on June 10, 1776, Maha Thiha Thura decided to call off the invasion. He wanted to ensure that his son-in-law and heir-apparent Singu Min succeed the throne. The withdrawal's longterm impact was that the Burmese would lose most of the old Lan Na Kingdom, which had been under Burmese suzerainty since 1558. The Burmese still retained Chiang Saen, a region in northern Lan Na but they would lose that in Bodawpaya's disastrous invasion of Siam.
Aftermath
After the death of the Burmese king Hsinbyushin the Burmese were plunged into their own dynastic struggles. In 1776, the new monarch Singu Min sent Maha Thiha Thura to invade Lanna again with such a huge army that Lord Vichianprakarn of Chiang Mai had to abandon the city. Chao Phraya Surasi and Lord Kawila of Lampang retook Chiang Mai from the Burmese but decided to leave the city abandoned as there was no population to fill the city. No further Burmese invasions came as Singu staged his dynastic purges on the princes and Maha Thiha Thura himself.
