[3] King Taksin himself with the general Chen Lian (陳聯) led the fleet to attack Hà Tiên, leading to the Siamese-Vietnamese War (1769–1773).

King Ang Ton fled to Saigon under the protection of the Nguyen Lord Nguyễn Phúc Thuần.

Cambodian nobles, led by Chauvea Tolaha Mu and his brother Oknha Decho Then, were dissatisfied with King Ang Non's pro-Siamese stance.

Nguyễn Phúc Ánh sent Vietnamese army to support Tolaha Mu, who arrested and murdered King Ang Non in 1779.

[5] Taksin ordered Youmreach Baen arrested and imprisoned at Thonburi but Chaophraya Chakri secured his pardon and release.

[7] Emperor Gia Long of the Vietnamese Nguyen dynasty also invested Ang Chan as the King of Cambodia next year in 1807.

In the same year, the Burmese invaded Phuket and King Rama II requested supporting troops from Cambodia to defend Bangkok.

Nguyễn Văn Nhơn the governor of Saigon led the Vietnamese troops of 1,000[5] men to take defensive position at Longvek against possible Siamese offensives.

The Siamese-Vietnamese standoff lasted for four months until Nguyễn Văn Nhơn pulled the troops back to Saigon in January 1811 but Phraya Rongmueang remained in Battambang.

Ang Chan then decided to leave Oudong on April 9, 1812, along with the royal family to take refuge in Phnom Penh.

[7] Nguyễn Văn Thoại provided boat vessels for the Cambodian king and his family to travel at Phnom Penh.

Yommaraj Noi and the Siamese army arrived in Oudong to find out that the Cambodian king had escaped to Phnom Penh.

Chaophraya Yommaraj Noi sent reconciliatory messages[8] to Ang Chan and Nguyễn Văn Nhơn, declaring that the Siamese intention was to peacefully settle the conflicts.

[8] Gia Long replied that the Prince Ang Sngoun was responsible for the incidents because he stirred up the events and was not a loyal subject to his elder brother who was also his overlord.

In April 1813, Gia Long ordered Lê Văn Duyệt[7] and Ngô Nhân Tịnh to bring troops from Huế to Saigon to escort Ang Chan back to Cambodia.

In May, Lê Văn Duyệt led the Vietnamese troop of 13,000[9] men to bring Ang Chan back to Phnom Penh with the Siamese envoys presented in the entourage as witnesses.

After the Siamese envoys and officials had returned to Battambang, Lê Văn Duyệt proposed to build a new citadel and royal city for Ang Chan.

[8] Lê Văn Duyệt then constructed a new citadel for Ang Chan at Phnom Penh called "Banteay Keav".

[7][8] Nguyễn Văn Thoại was appointed as bảo hộ[10] or Protector of Cambodia and was assigned with Vietnamese troops of 1,500 men[7] to guard King Ang Chan.

Ang Chan also rewarded his meritorious subjects with high positions, with Oknha Bovorneayok becoming Chakrey Suat and Tuan Pha, a Cham[7] general, becoming the Youmreach.

King Ang Chan then ordered Samdech Chauponhea Tei to lead Cambodian army to Battambang to collect stalactites and bat guano as taxes.

Samdech Chauponhea Tei[7] led the Cambodian army to Battambang in 1815 and sent Oknha Surkealok the governor of Pursat ahead as vanguard.

Samdech Chauponhea Tei told the Vietnamese court that he marched Cambodian army to Battambang with peaceful intentions only to collect taxes.