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THE BURMESE-SIAMESE WAR OF 1765-67

Vitor Vieira Vasconcelos

PhD in Natural Sciences Stockholm Environment Institute – Asia Centre

November 2015

The Burmese-Siamese war of 1765-67 ended the four-century old Ayutthaya

kingdom, with the siege and sack of its capital. This study aims to show how geographical

factors influenced the siege, the battle strategies and the outcomes of the war.

The objective of the war, alleged by the Burmese government, was to consolidate

the control over Tenasserim coast territory, important for maritime trade (James, 2004, p.

302). In the previous Burmese-Siamese war of 1759-1760, the Burmese regained control

of the Tavoy frontier but the control over Tenasserim was still fragile and inconclusive

(Figure 1). In addition, the Burmese government claimed that the Siamese were

supporting rebels in the Burmese border regions (Baker at al., 2009, p. 21).

The war begun in 1765, when 20,000 burmese soldier invaded Northern Siamese

Kingdom, while other three southern armies of over 20,000 soldiers also came from the

South (Maung Maung Tin, 1905), in a pincer movement, as depicted in Figure 2. It was

also relevant that, conquering the northern territories, the Burmese rallied more soldiers

that marched against Ayutthaya (Phraye, 1883, p. 187,188).

Although numerically superior, the Thai defenses had much less experience on

wars, especially regarding coordination and military planning (Harvery, 1925, p. 250-253;

Phraye, 1883 p. 188-189). The Burmese already had experiences in many wars since

1740, as well as in internal civil wars, while the Thai army commanders had little battlefield

experience despite the 1760 war against the Burmese (Lieberman, 2003).

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Figure 1 – Routes and territories in the Burmese-Siamese War of 1759-1760. The orange

territory was conquered by Burma, but the control on the black territory was still tenuous.

The red arrows show the advance of the Burmese army and the green arrow shows the

retreat of the Burmese Army. Source: Hybernator (2010).

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Figure 1 – Route of the four Burmese armies in the Burmese-Siamese war of

1765-67. Source: Aristitleism (2011)

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The Burmese kingdom faced a territorial dilemma in the Burmese-Siamese war,

because at the same time that they aimed at conquering Siam territory at their eastern

front, they were facing the risk of being invaded by China, which had on of the largest

armies in the world, through the Northern boundary. Actually, when the Burmese army

reached Ayutthaya, the Chinese have already started their invasion. Aware of that

situation, the Siamese planned that if they could endure the siege for a long time, the

Burmese would have to retreat in order to defend their country from the Chinese. On the

other hand, the Burmese bet that the Chinese war would be just a minor territorial dispute

and the war against Siam would bring a much vaster territory to their kingdom.

The weather and hydrological processes played a major whole in the strategies of

the siege of Ayutthaya. Ayutthaya lies in an island in the junction of Chao Phraya, Lop

Buri and Pa Sak Rivers (Figures 3 and 4), and its defenses were structured based on this

natural characteristics. In the Chao Phraya River Basin, the tropical monsoon climate

generates a rainy season that starts from May to October (Figure 5), causing wide floods

(Rungdilokroajn, 1992). The average rainfall varies from 1000 to 1500 mm/year and 85%

of it falls in the rainy season (Sayama et al., 2014).

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Figure 3 – Map of ancient Ayutthaya. Author: Nicolas Bellin 1752

Figure 4 – Landscape of ancient Ayutthaya. Author: Johannes Vingboons, 1665.

Figure 5 – Average rainfall and streamflow of the Central Plain of the Chao Phraya

River Basin. Data from Koontanakulvong (2006).

0

100

200

300

400

500

600

700

800

900

May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr

Average Rainfall (mm/month)

Average Streamflow (million cubic

meters/month)

Ra

infa

ll(m

m/m

on

th)

Str

ea

mfl

ow

(m

illi

on

cu

bic

me

tte

rs/m

on

th)

Month

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The Burmese army started their march in the dry season, in order to increase

mobility (Harvey, 1925, p. 242). The southern armies avoided the coast of the Gulf of

Thailand, were they could be easily surrounded by the numerically superior Siamese

defenses (Ayeadawbon, 1961, p. 147-148).

The siege on Ayutthaya started in January 1766. The original plan of the Siamese

was to resist until the rainy season, and then the floods would hopefully make the

besiegers retreat. However, during the flood period the Burmese army did not retreat, but

got sheltered on elevated high spots. The new situation momentarily equilibrated the war

and the Thai and Burmese started to attack each other using their boats.

The Burmese army also used their boats to prevent rice supplies to enter

Ayutthaya. As a result, by the end of the rainy season the city was already running low of

supplies (Phraye, 1883, p. 189).

In the end of 1766, already in the dry season, the Burmese army built earthworks

to access the city of Ayutthaya (Harvey, 1925, p. 252) and started to dig tunnels under

the city walls, to mine them (Maung Maung Tin, 1905, p. 303). In March of 1767, the

Burmese finally invaded, burnt, sacked and destroyed the city, which was already starving

by that time.

However, at the period of Ayutthaya invasion, the Chinese army sent a new large

offensive in the north of Burma’s territory, forcing the Burmese army to withdraw from

Siam kingdom (Phraye, 1883, p. 190). Without the Burmese presence, the Siamese local

chiefs started to dispute the political power over the region in a civil war. As a result from

the war, Burma retained only the control of Tenasserin coast territory.

After King Taksin reunified the Thai kingdom, the Siamese kingdom moved its

capital to Thonburi in 1767 and then to Bangkok in 1782. The ruins of Ayutthaya became

world heritage by UNESCO in 1991, and thousands of tourists that visit there every year

learn about the Burmese-Siamese war of 1765-67. The historical grief from Thai people

against the Burmese attack to Ayutthaya, was one of the main alleged motivations for the

Thai government to sponsor separatist movements of ethnic minorities located in the

Burmese borders with Thailand, during the last centuries (Myint-U, 2006, p. 299 and 308).

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References:

Aristitleism (2011). Sketch-map of advance of Burmese troops towards Ayutthaya City, in the Burmese-Siamese War (1765-1767).

Baker, Chris, Christopher John Baker, Pasuk Phongpaichit (2009). A history of Thailand (2 ed.). Cambridge University Press. ISBN 9780521767682.

Harvey, G. E. (1925). History of Burma: From the Earliest Times to 10 March 1824. London: Frank Cass & Co. Ltd.

Hybernator (2010) The war path of Burmese-Siamese War (1759-1760).

James, Helen (2004). Burma-Siam Wars and Tenasserim. In Keat Gin Ooi. Southeast Asia: a historical encyclopedia, from Angkor Wat to East Timor, Volume 2. ABC-CLIO. ISBN 1-57607-770-5.

Koontanakulvong S (coord) (2006) The study of Conjunctive use of Groundwater and Surface Water in Northern Chao Phraya Basin Final Report. Department of Groundwater Resources. Chulalongkorn University

Letwe Nawrahta and Twinthin Taikwun (c. 1770). Hla Thamein, ed. Alaungpaya Ayedawbon (in Burmese) (1961 ed.). Ministry of Culture, Union of Burma..

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Sayama, T., Tatebe, Y., Iwami, Y., & Tanaka, S. (2014). Hydrologic sensitivity of flood runoff and inundation: 2011 Thailand floods in the Chao Phraya River basin. Natural Hazards and Earth System Sciences Discussions, 2(11), 7027-7059.