Burmese–Siamese War (1759–1760)

The control of Tenasserim coast (present-day Mon State and Tanintharyi Region in Myanmar) in the early 18th century was divided between Burma and Siam, with the Burmese controlling down to Tavoy (Dawei) and the Siamese controlling the rest. Throughout history, both kingdoms had claimed the entire coast (the Siamese to Martaban, and the Burmese to Junkceylon), and control had changed hands several times. The Burmese Pagan Dynasty controlled the entire coast until 1287. Throughout 14th and 16th centuries, Siamese kingdoms (first Sukhothai, later Ayutthaya) controlled much of the coast, up to just south of present-day Mawlamyaing. In the mid-16th century, the Burmese under Toungoo kings Tabinshwehti and Bayinnaung tried to regain the coast, first failing in 1548, and finally succeeding in 1564 when they conquered all of Siam for the first time. The Siamese revolted in 1584, and under their king Naresuan regained the lower coast by 1593 and the entire coast by 1594. The Burmese retook the upper coast down to Tavoy in 1615, but failed to recover the rest.[1]

This arrangement lasted until 1740 (although the Siamese unsuccessfully tried to take the upper coast in 1662–65). During this period, Mergui on the Andaman Sea was the primary port of Siam through which its trade with India and the West was conducted.[1]

In 1740, the Mons of Lower Burma revolted against the Toungoo Dynasty and founded the Restored Hanthawaddy Kingdom based in Pegu. Throughout the 1740s, the Hanthawaddy forces were winning against Upper Burma-based Toungoo armies. The Siamese were concerned by another rising power in Burma since a strong Burma historically meant future invasions to Siam. After all, it was then Pegu-based Toungoo Dynasty in the 16th century that turned to Siam after having first conquered Upper Burma. Concerned, the Siamese court readily gave protection to the Burmese governors of Martaban and Tavoy who had fled to Siam. In 1745, they sent a diplomatic mission to Ava (Inwa) to evaluate the political situation there, and were received by the Burmese king Mahadhammaraza Dipadi. They saw an Ava court that was on its last legs.[13] By 1751, Restored Hanthawaddy forces were closing in on Ava. The Siamese concerns about the emergence of another strong dynasty based in Pegu appeared imminent.

Perhaps as a precautionary measure, the Siamese decided to move their forward base into the upper coast in 1751.[14][15] Or it could have been an opportunistic land-grab while Restored Hanthawaddy armies were deeply involved in Upper Burma. While it remains unclear as to whether the Siamese ever intended or possessed the military capability to go beyond the coast into mainland Lower Burma, the Siamese action nonetheless rang alarm bells in Pegu. Deeply concerned, the Hanthawaddy leadership withdrew two-thirds of their army back down to Lower Burma immediately after they had toppled the last Toungoo king in April 1752.[16]

This redeployment of Hanthawaddy troops proved a critical turning point in Burmese history as it gave nascent Upper Burmese resistance groups much needed breathing room. The Hanthawaddy command left less than 10,000 men to pacify all of Upper Burma.[16] Historians call the redeployment premature, pointing out that the Siamese threat was never as grave as any counterforce that could rise from Upper Burma, the traditional home of political power in Burma. Taking advantage of light Hanthawaddy troops, one resistance group, the Konbaung Dynasty led by Alaungpaya, drove out Hanthawaddy troops from Upper Burma by May 1754. Konbaung armies invaded Lower Burma in 1755, and captured Pegu in 1757, ending the 17-year-old Mon kingdom.[17][18]

For the Siamese, the situation they had feared—the emergence of a strong power in Burma—had come true although it was the Upper Burma-based Konbaung Dynasty, not Restored Hanthawaddy they were originally concerned about (ironically, the Siamese were partly responsible for the initial success of Konbaung Dynasty as their occupation of the upper coast helped divert the main body of Hanthawaddy troops southward). In a policy switch, they now actively supported Mon resistance groups still operating in the upper coast where Burmese control was still nominal.

After the Konbaung sack of Pegu in 1757, the governors of Martaban and Tavoy had sent in tribute to Alaungpaya to avoid the same fate[19] (the Tavoy governor turned out to be paying dual tribute, and would be executed later). While the Burmese now claimed the upper Tenasserim coast down to Tavoy, their hold of Lower Burma was still tenuous and especially in the southernmost Tenasserim coast it was largely nominal. Indeed, once Konbaung armies returned north in 1758 for their expeditions in Manipur and northern Shan States, the Mons of Lower Burma rose in rebellion.[20]

The rebellion initially was successful, driving out the Burmese governor from Pegu. It was eventually put down by local Konbaung garrisons. Mon resistance leaders and their followers fled to the Siamese controlled Tenasserim coast and remained active there. The border became the scene of chronic raiding and counter-raiding.[20][21]

In 1758, at the death of King Borommakot, Ayutthaya was the wealthiest city in mainland Southeast Asia. After a brief succession struggle, one of Borommakot's sons, Ekkathat, emerged as king after another son Uthumphon gave up the throne to become a monk. As king, Ekkathat faced the developing situation in the west left behind by his father. He refused Alaungpaya's demands, and prepared for war.

The Siamese battle plan was a defensive one. Ekkathat improved the defenses of Ayutthaya and took up prepared positions all along the routes that the previous Burmese invasions had followed. The main Siamese forces were massed to the westward approaches of Ayutthaya[27] (previous Burmese invasions had always come via the Three Pagodas Pass in the west, and sometimes also by Chiang Mai in the north). Ekkathat's Ayutthaya defenses included a small number of Dutch-manned warships, as well as several cannon-mounted war-boats manned by foreigners ("feringhis and Mahomedans").[28] To guard the coast and the Gulf of Siam flank, he deployed two smaller armies, totaling 20 regiments (27,000 men, 1,300 cavalry and 500 elephants). Of the total, only 7,000 infantrymen and 300 cavalry were deployed in the Tenasserim coast itself.

Ekkathat asked his old rival and brother Uthumphon to leave the monkhood, and made him the commander-in-chief.

The Burmese too had begun to assemble their invasion force, starting during their new year celebrations in April 1759, gathering troops from all over Upper Burma, including from recently conquered northern Shan States and Manipur. By late 1759, Alaungpaya had massed a force of 40 regiments (40,000 men including 3,000 cavalry) at Yangon. Of the 3,000 cavalry, 2,000 were Manipuri "Cassay Horse", who had just been press-ganged into Alaungpaya's service after the Burmese conquest of Manipur in 1758.[29]

The Burmese battle plan was to go around the heavily defended Siamese positions along the Three Pagodas Pass-Ayutthaya corridor. They selected a longer but less defended route: Go south to Tenasserim, cross the Tenasserim Hills over to Gulf of Siam, and turn north to Ayutthaya.[30] To that end, the Burmese had assembled a fleet of 300 ships to transport a portion of their troops directly to the Tenasserim coast.[29]

Alaungpaya was to lead the invasion personally, and his second son Hsinbyushin was his second-in-command. His first son Naungdawgyi was left to administer the country (two of his other sons, a 14-year-old Bodawpaya and a 16-year-old Amyint Mintha were to lead a small battalion each[31]). Also in his service were his top generals including the likes of Minkhaung Nawrahta who like all Burmese leadership had plenty of military experience. Some in the court urged him to stay behind and allow Hsinbyushin to lead the operation but the king refused.[32]

On 21 December 1759 (3rd waxing of Pyatho 1121 ME), Alaungpaya and his invasion army, numbering 46,000 infantrymen and 3,500 cavalry left Yangon for Martaban at the frontier. At Martaban, instead of taking the usual route via the Three Pagodas Pass, the Burmese invaded south, with Hsinbyushin leading the vanguard of six regiments (5,000 men, 500 horses) to Tavoy.[34] Tavoy was easily occupied, and its hapless governor, who was torn between two greater powers and paying dual tribute, was executed.[6] The Burmese army paused for three days for the rest of army to arrive by land and by sea.

After the rest of the Burmese army had arrived, Alaungpaya's army marched and besieged Mergui. The vastly outnumbered Siamese garrison of 7,000 infantrymen and 300 cavalry was easily overran by the Burmese army. In less than two weeks of the war, the Burmese had captured both Mergui and the town of Tenasserim, and controlled the entire Tennaserim coast.[34]

Knowing that the main Siamese armies would be moving to their south to meet his armies, Alaungpaya did not pause. The Burmese troops quickly moved eastward, crossed over the Tenasserim Hills, and reached present-day Prachuap Khiri Khan Province on the shore of the Gulf of Siam.[19] The southern flank was defended by a Siamese army of 20,000 infantrymen, 1,000 cavalry and 200 elephants, in addition to the 7,000-strong Siamese army that retreated from Tenasserim.[35] Likewise, because of the minimal Siamese resistance in the coast, the 40,000-strong Burmese army was still largely intact although the invasion army was hemmed in the narrow strip of coastline by the Gulf of Siam. The Siamese defenses met the invading force outside Kui Buri but were defeated and forced to retreat.

After defeating the Siamese army at Kui Buri, the Burmese marched 40 km and faced another army at Pranburi. The Burmese won the battle and took the city. After capturing Pranburi, the Burmese encountered much stiffer Siamese resistance.

Seeing the success of the Burmese invasion, Ekkathat reinforced the front with a land and naval force consisting of 60,000 men with 4,000 guns. The guns in the land force were mounted on carriages and elephants while those in the naval force were placed on war boats.[7] Over the next two months (February and March 1760), battle-hardened Burmese forces overcame several spirited Siamese stands, and took Phetchaburi and Ratchaburi.[6][35]

By capturing Ratchaburi, the Burmese had now fought their way out of the narrow Kra Isthmus and made it to mainland Siam by late March 1760 (early Tagu 1121 ME). As the Burmese forces marched towards Ayutthaya, a Siamese force of 30,000 infantrymen and 3,000 cavalry was sent to halt the Burmese army from crossing the Tha Chin River in Suphan Buri. The Burmese launched a three pronged attack (led by Hsinbyushin in the center flanked by generals Minkhaung Nawrahta and Minhla Thiri) on heavily fortified Siamese positions around the city. The Burmese took heavy losses but ultimately prevailed, taking five senior Siamese commanders and their war elephants.[6][36]

Siamese city of Ayutthaya, c. 1662-63

Despite heavy losses at Suphan Buri, the Burmese army had to march on towards Ayutthaya. They could not rest since the monsoon season was a little over a month away. As Ayutthaya was surrounded by several rivers, laying siege in the rainy season would have been a daunting task. The whole country would be under several feet of water. Half of the remaining Burmese forces were down with dysentery and Alaungpaya himself was not well.[12]

Nevertheless, the Burmese arrived at the environs of Ayutthaya on 11 April 1760. The Siamese sent a new 15,000-strong army to meet the invaders. But the force, which was probably made up of fresh conscripts, was promptly defeated by the battle-hardened Burmese army, though no longer in full strength. To avoid a long siege, the Burmese king sent envoys into the city, calling upon the Siamese king to surrender, promising that he would not be dethroned. Ekkathat sent envoys of his own to negotiate but found Alaungpaya's terms unacceptable, and negotiations broke down completely.[11] Starting on 14 April, during the Burmese and Siamese new year's celebrations, the Burmese began bombarding the city itself for the next three days.[6]

But the Burmese king's health deteriorated rapidly. He was suffering from either dysentery[11] or scrofula.[6] According to the Siamese sources, he was wounded by the bursting of a shell from a battery whose installation he was personally supervising but the Burmese sources definitely state that he became ill with dysentery. There was no reason for the Burmese chronicles to hide the truth since it is more glorious for a Burmese king to die of wounds received on the battlefield than to die of a common ailment. Moreover, if he had been wounded in the full view of the army, it would have been known to the whole army, creating confusion.[11]

The Burmese command kept Alaungpaya's serious illness a secret and ordered a general withdrawal, giving the excuse that the king was indisposed. The king selected the friend of his childhood, Minkhaung Nawrahta, for the signal honor of commanding the rearguard. These were the "pick of the army"—500 cavalry and 6,000 infantrymen, every man of whom had a musket. Minkhaung Nawrahta spread them out and waited. It was two days before the Siamese realized that the main Burmese army had left. The full Siamese force then came out. His men watched the ring closing round them, and fearing to be cut off, pleaded the general to let them fight further back. But he said "Friends, the safety of our Lord the King lies in our keeping. Let us not fight further back lest the sounds of guns break his further sleep." With his leadership, the Burmese forces withdrew in good order, collecting army stragglers along the way.[11][12]

Alaungpaya died on 11 May 1760 near Martaban, after being rushed by the advance guard. With his death, the war ended.