The Burmese–Siamese War (1547–1549) (Burmese: ယိုးဒယား-မြန်မာစစ် (၁၅၄၇–၄၉); Thai: สงครามพม่า-สยาม พ.ศ. 2090–2092), also known as the Tabinshwehti war (Thai: สงครามพระเจ้าตะเบ็งชเวตี้) was the first war fought between the Toungoo dynasty of Burma and the Ayutthaya Kingdom of Siam, and the first of the Burmese–Siamese wars that would continue until the middle of the 19th century. The war is notable for the introduction of early modern warfare to the region. It is also notable in Thai history for the death in battle of Siamese Queen Suriyothai on her war elephant; the conflict is often referred to in Thailand as the War that Led to the Loss of Queen Suriyothai (สงครามคราวเสียสมเด็จพระสุริโยไท).
The casus belli have been stated as a Burmese attempt to expand their territory eastwards after a political crisis in Ayutthaya as well as an attempt to stop Siamese incursions into the upper Tenasserim coast. The war, according to the Burmese, began in January 1547 when Siamese forces conquered the frontier town of Tavoy (Dawei). Later in the year, the Burmese forces led by Gen. Saw Lagun Ein retook the Upper Tenasserim coast down to Tavoy. Next year, in October 1548, three Burmese armies led by King Tabinshwehti and his deputy Bayinnaung invaded Siam through the Three Pagodas Pass. The Burmese forces penetrated up to the capital city of Ayutthaya but could not take the heavily fortified city. One month into the siege, Siamese counterattacks broke the siege, and drove back the invasion force. A truce was agreed in February 1549. The Burmese negotiated a safe retreat in exchange for the return of two important Siamese nobles (the heir apparent Prince Ramesuan, and Thammaracha of Phitsanulok) whom they had captured.
The successful defense preserved Siamese independence for 15 years. However, this war was not decisive. The next Burmese invasion in 1563 would force a Siamese surrender in February 1564, and make Ayutthaya a vassal state of Burma for the first time.
Background
Rise of Toungoo Dynasty
Burma in the 15th century was divided into four principal power centers: the Ava Kingdom in present-day central Burma, the Mon-speaking Hanthawaddy kingdom on the southern coast, the Mrauk-U Kingdom (Arakan) in the west, and various Shan States in the east and the north. Beginning in the 1480s, Ava began to disintegrate into even smaller kingdoms. By the early 15th century, Ava's former vassals—Mohnyin (and its allies Confederation of Shan States) in the north and the Prome Kingdom (Pyay) in the south—were regularly raiding their former overlord's territory with increasing frequency and intensity.
During this period of tumult, Mingyi Nyo, then governor of Toungoo (Taungoo), a small region located at the southeastern corner of Ava Kingdom also declared independence in 1510, and largely stayed out of the internecine fighting in the following years. When Ava fell to the combined forces of the Confederation and Prome in 1527, many people fled to Toungoo, the only region in Upper Burma at peace.
In 1530, Mingyi Nyo's son 14-year-old Tabinshwehti succeeded him as king. Toungoo's stability continued to attract manpower from the surrounding regions, especially after 1533 when the Confederation sacked its erstwhile ally Prome. The tiny Toungoo was now the only ethnic Burman-led kingdom, and one surrounded by much larger kingdoms. Fortunately for Toungoo, the Confederation was distracted by internal leadership disputes, and Hanthawaddy, then the most powerful kingdom of all post-Pagan kingdoms, was weakly led. Tabinshwehti decided not to wait until the larger kingdoms' attention turned to him.
In 1534, Tabinshwehti and his deputy Bayinnaung, then a couple of 18-year-olds, launched their first military campaign against Hanthawaddy. It was the first of a series of wars by Toungoo that would engulf western and central mainland Southeast Asia for the next 80 years. In 1538–1539, the upstart kingdom captured Hanthawaddy's capital Pegu (Bago), and in May 1541, Martaban (Mottama) and Moulmein (Mawlamyaing). Significantly, for the first time, the Burmese and the Siamese shared a common border in the upper-Tenasserim coast.
For the next six years, Toungoo was busy fighting against Hanthawaddy's allies: Prome (1542), the Confederation (1542–1544), and Prome's ally Mrauk-U (1546–1547). On the eve of the Siamese war, in 1547, Toungoo controlled a Lower Burma region from Pagan (Bagan) in the north to Moulmein in the south.
Crisis in Ayutthaya
King Chairacha of Ayutthaya was a scion of the Suphannaphum Dynasty, which took control of Siam from the Uthong Dynasty in 1409. He came to the throne in 1533 after usurping the crown of his five-year-old nephew, Phra Ratsadathirat, who had reigned for only four months. The boy's father was King Borommarachathirat IV, Chairacha's half-brother. The child-king was subsequently executed by his uncle. King Chairacha died in 1546 after reigning for thirteen years, leaving the throne to his eleven-year-old son, Prince Kaeofa, who was crowned King Yot Fa.
As the new king had not come of age, the role of regent was assumed by his mother, Chairacha's chief consort Si Sudachan (ศรีสุดาจันทร์, also spelled Sri Sudachan), who was a descendant of the Uthong royal house. Chairacha's half-brother and Uparaja, Prince Thianracha, was another contender for the regency. To avoid court intrigues and conflict with Si Sudachan, Prince Thianracha retreated to a monastery as a monk. It is said that even before the previous King's death, Si Sudachan was having an adulterous relationship with a paramour styled Khun Chinnarat, who was keeper of the Royal chapel or cloister (หอพระเทพบิดร, Ho Phra Thep Bidon) within the Royal Palace of Ayutthaya. Fernão Mendes Pinto, a contemporary Portuguese explorer, recorded a rumour alleging that Si Sudachan had poisoned her husband in order to take control of the throne, and perhaps to restore the fallen House of Uthong to power. In support of these allegations, she had many prominent officials executed, including the aged and high-ranking Phraya Mahasena (Minister of Defence), and replaced them with her favourites. It was also recorded that she was heavily pregnant and soon gave birth to a daughter; unable to conceal this secret, she mounted a coup, removed her son and put her paramour on the throne. He was crowned as King (or Khun) Worawongsathirat. It was said that the young King Yot Fa was either executed or poisoned by his mother.
Worawongsathirat's reign was short. Within 42 days several nobles and government officials of Ayutthaya plotted to remove him from the throne. The conspirators were led by Khun Phiren Thorathep, a descendant on his father's side to the kings of Sukhothai and a relation on his mother's side to King Chairacha. The usurper was lured from the safety of the palace into the jungle with a promise of capturing a large elephant. As the usurper king, Si Sudachan and their infant daughter proceeded by royal barge, Khun Phiren Thorathep and his conspirators sprang an ambush, killing all three. Thianracha was immediately invited to leave the Sangha and assume the throne as King Maha Chakkraphat. One of his first acts was to appoint Khun Phiren Thorathep as King of Sukhothai (but as a vassal to himself) with a capital at the great fortified town of Phitsanulok. The king then bestowed upon him the title Maha Thammaracha (a title used by the last four kings of Sukhothai), along with the hand of his daughter Princess Sawatdirat in marriage.
Tenasserim (1547–1548)
The war began in 1547. The casus belli has been stated as an attempt by the Toungoo Dynasty of Burma to expand its territory eastwards after a political crisis in Ayutthaya as well as an attempt to stop Ayutthaya's incursions into the upper Tenasserim coast. According to the Burmese chronicles, a Siamese force of 6,000 had occupied Tavoy (Dawei) in the Upper Tenasserim coast, which he considered his territory, by January 1547. As frontiers in the pre-modern period were less defined and often overlapped, the "occupation" may have been an attempt by Ayutthaya to reinforce the frontier town, which was claimed by Toungoo. At any rate, Tabinshwehti sent a sizable force of 12,000 (8,000 army, 4,000 navy) led by Saw Lagun Ein, viceroy of Martaban, to take over Tavoy c. October/November 1547. A joint land-naval attack on Tavoy drove out the Siamese forces led by the Lord of Kanchanaburi to lower Tenasserim.
Invasion of mainland Siam (1548–1549)
Burmese battle plan
Tabinshwehti was not satisfied, and planned an invasion of Siam itself. By October 1548, he had assembled another 12,000-strong force that also included about 400 Portuguese mercenaries led by Diogo Soares. The invasion force would have been equipped with the conventional weapons of the day: swords, bow and arrows, and spears. The more elite members would also carry matchlocks or muskets. These early modern weapons having been introduced to the two kingdoms by the Portuguese a few decades earlier.
Tabinshwehti took personal command and gathered his forces at Martaban (Mottama). The invasion forces were organized into three main armies: the vanguard army led by Bayinnaung, the main army led by Tabinshwehti, and the rearguard army led by Thado Dhamma Yaza and Mingyi Swe, each with a strength of 4,000 troops. Their route of invasion was via the Three Pagodas Pass towards Kanchanaburi, and then to the capital Ayutthaya.
Start of invasion
On 14 October 1548 (13th waxing of Tazaungmon 910 ME), the three Burmese armies left Martaban to start the invasion. The armies marched along the Ataran River toward the Three Pagodas Pass, entered Siam along the Khwae Noi River to the town of Sai Yok, then overland towards the Khwae Yai River. From there they travelled by boat toward the town of Kanchanaburi. Tabinshwehti travelled in great state with a massive retinue of elephants and servants. Many of these elephants carried muskets and bronze cannon; these were kept close to the king. Royal elephants were rafted across rivers, while the ordinary war elephants marched upstream to a ford. The Burmese king was accompanied by his crown prince Bayinnaung, Bayinnaung's thirteen-year-old son Nanda, and many richly attired lords. Hundreds of workmen marched ahead of the king's retinue, to pitch a richly decorated wooden camp, painted and gilded for the King's use, only to pack it up and pitch it at a new location every day.
The invasion initially met little resistance, as the Burmese forces were too large for the small guard posts around the border. Upon hearing of the Burmese invasion, Maha Chakkraphat mobilized his kingdom, then gathered his forces at Suphanburi, a town just west of Ayutthaya. When Tabinshwehti and his army arrived at the walled town of Kanchanaburi, they found it completely deserted. About a month into the invasion, mid-November 1548, the King of Burma then continued his march eastward, capturing the villages of Ban Thuan, Kaphan Tru, and Chorakhe Sam Phan. The Burmese continued their advance and captured the ancient town of Uthong as well as the villages of Don Rakhang and Nong Sarai and closing in on Suphanburi. When the Burmese attacked the town, Siamese defenders could not withstand the onslaught and retreated towards Ayutthaya. Tabinshwehti ordered his army southeast along two canals, and crossed the Chao Phraya river near Phong Phaeng. From here he encamped his army directly north of the Siamese capital of Ayutthaya on a field called the Lumpli plain.
Battle of Ayutthaya
At the outskirts
Maha Chakkraphat decided to leave the capital with his forces, to engage Tabinshwehti and test the Burmese strength. On this occasion, he mounted his chief war elephant. Accompanying him were his Chief Queen, Sri Suriyothai, and one of their young daughters, Princess Boromdilok, the two riding together on a smaller war elephant. Both royal ladies were dressed in male military attire (helmet and armour), with the queen wearing the uniform of an Uparaja. Also accompanying their father on elephant mounts were two sons, the Uparaja and heir apparent, Prince Ramesuan, and his brother Prince Mahin.
A battle certainly ensued although there are naturally two accounts as to what actually took place. According to the Burmese chronicles, the Burmese command fielded an army led by Thado Dhamma Yaza, the Viceroy of Prome, as a decoy and the two armies lurked on the flanks in order to encircle any overstretched Siamese forces. As planned, the Siamese vanguard troops pressed on Thado Dhamma Yaza's army, allowing Bayinnaung's army waiting on the left flank to encircle the Siamese forces, which subsequently were wiped out. Tabinshwehti's army on the right flank drove back the remaining Siamese forces into the city.