Vietnam and Cambodia In 1784–1785, the last of the
Nguyễn Lords,
Nguyễn Ánh, convinced Rama I to give him forces to attack Vietnam, which was then under the control of the
Tây Sơn brothers. However, the joint Nguyễn-Siam fleet was destroyed in the
Battle of Rạch Gầm-Xoài Mút in the
Mekong Delta region. Nguyễn's appeal for Siamese assistance enabled the Siamese to exert considerable political influence over Nguyễn's court. Mac Tu Sinh, the son of
Mạc Thiên Tứ and his Siamese wife, was raised among the Siamese, and held office as the governor of
Hà Tiên until his death in 1787. Ngo Ma, a general of Siamese descent, was appointed as its acting governor in Mac's place. Nguyễn Ánh also took refuge in Siam at the King's court waiting for the opportunities to defeat Tây Sơn. These episodes demonstrated Rama I's willingness to extend Siamese power beyond his Kingdom. In Cambodia, King
Reamraja (Ang Non II) was deposed in 1779 and the throne was given to the young prince
Ang Eng. However, the pro-Vietnamese policies of certain Cambodian aristocrats under Ang Eng alarmed Rama I. As a result, Rama I had Ang Eng captured and deported to Bangkok, where Rama adopted him as his son, the purpose of which was to impose pro-Siamese sentiments on him. Rama I also imposed
Chaophraya Aphaiphubet as the Regent of Cambodia. Nguyễn Ánh secretly left for Vietnam in 1787, leaving Rama I a note. Ánh managed to recapture
Saigon by 1788 and later ascended as Emperor Gia Long in 1802. In 1794, upon Ang Eng's majority, Rama I reinstalled him as the Neareay Reachea III. The area around
Siem Reap and
Battambang was annexed by Siam, and were governed by Aphaiphubet. However, Rama I allowed these territories to be ruled in accordance with Cambodian traditions.
Wars with Burma Soon King
Bodawpaya of Burma started to pursue his ambitious campaigns to expand his dominions over Siam. The
Burmese–Siamese War (1785–1786), also known in Siam as the "Nine Armies War" because the Burmese came in nine armies, broke out. The Burmese soldiers poured into Lanna and Northern Siam. Siamese forces, commanded by
Kawila, Prince of Lampang, put up a brave fight and delayed the Burmese advance, all the while waiting for reinforcements from Bangkok. When
Phitsanulok was captured,
Anurak Devesh the
Rear Palace, and Rama I himself led Siamese forces to the north. The Siamese relieved
Lampang from the Burmese siege. In the south, Bodawpaya was waiting at
Chedi Sam Ong ready to attack. The
Front Palace was ordered to lead his troops to the south and counter-attack the Burmese coming to
Ranong through
Nakhon Si Thammarat. He brought the Burmese to battle near
Kanchanaburi. The Burmese also attacked Thalang (
Phuket), where the governor had just died. Chan, his wife, and her sister Mook gathered the local people and successfully defended Thalang against the Burmese. Today, Chan and Mook are revered as heroines because of their opposition to the Burmese invasions. In their own lifetimes, Rama I bestowed on them the titles
Thao Thep Kasattri and Thao Sri Sunthon. The Burmese proceeded to capture
Songkhla. Upon hearing the news, the governors of
Phatthalung fled. However, a monk named Phra Maha encouraged the citizens of the area to take up arms against the Burmese; his campaign was also successful. Phra Maha was later raised to the nobility by Rama I. As his armies were destroyed, Bodawpaya retreated. The next year, he attacked again, this time constituting his troops as a single army. With this force Bodawpaya passed through the Chedi Sam Ong pass and settled in Tha Din Daeng. The
Front Palace marched the Siamese forces to face Bodawpaya. The fighting was very short and Bodawpaya was quickly defeated. This short war was called the
Tha Din Daeng campaign. ==Illness and death==