Cambodian rebellion (1840)

The Cambodian uprising of 1840 was a general uprising of Khmer people against direct Vietnamese rule in September 1840. In response to Siamese invasion of Cambodia and Southern Vietnam in 1833, the Vietnamese Nguyen dynasty had annexed Cambodia into Trấn Tây Province in 1835 with Ang Mey as puppet female ruler under Trương Minh Giảng^[1] the Vietnamese Governor-General of Trấn Tây or Cambodia, imposing direct rule, assigning Vietnamese administrators over the local indigenous Khmer aristocracy,^[2] pursuing Vietnamese-led economical and agricultural expansion and ethnocultural assimilation policies.^[3] Vietnamese rule over Cambodia was established with the consent of the pro-Vietnamese faction in Cambodia in order to repel and eliminate any Siamese influence or incursions into Cambodia but friction between the Khmers and the Vietnamese eventually led to the general uprising against Vietnam.

Not all of Cambodia was under Vietnam's Trấn Tây Province. Siam had earlier appropriated northwestern Cambodia, including Battambang and Siemreap, into its own direct rule in 1794. The Siam-held northwestern Cambodia, known in Thai historiography as Inner Cambodia, centered on Battambang, had been serving as the base for expansion of Siamese interests in Cambodia. Through this period of Vietnamese rule, the Siamese, from Battambang, had been looking for a ripening opportunity to reassert their domination over Cambodia. Defection of Cambodian Prince Ang Em from Siamese to Vietnamese side in 1839, dethronement of Queen Ang Mey, exile of Cambodian royalty and high-ranking Cambodian ministers in 1840 dissatisfied Khmer people, who viewed the Vietnamese as eroding their cultural identity and traditional governance. This Cambodian uprising against Vietnam in 1840 enabled Siam to push forward its candidate Prince Ang Duong for the Cambodian throne,^[1][4] instigating the Khmers to rise against the Vietnamese.

Cambodian uprising of 1840 undermined Vietnamese position in Cambodia, allowing the Siamese armies under Chaophraya Bodindecha to march into Cambodia in November 1840 to restore Siamese rule,^[1] leading to the Siamese–Vietnamese War of 1840–1842. In spite of their precarious position, the Vietnamese still held out against the invading Siamese. Death of the Vietnamese Emperor Minh Mạng in 1841 spelt the end to Vietnamese rule in Cambodia as the new Vietnamese ruler Thiệu Trị favored withdrawal of Vietnamese troops from Cambodia. Thiệu Trị ordered the general retreat of the Vietnamese from Cambodia in late 1841, thus ending the six-year direct rule of Vietnam over Cambodia. Vietnamese withdrawal allowed the Siamese to take control over Cambodia, bringing Cambodia into another period of Siamese domination.^[1]

In 1794, King Rama I of Siam sent the young Cambodian king Ang Eng to rule in person^[4] after twelve years of refuge or captivity in Bangkok. The Siamese king Rama also separated northwestern Cambodia including Battambang and Siemreap to be under Chaophraya Aphaiphubet Baen the first Siam-appointed governor of Battambang under direct Siamese rule. King Ang Eng of Cambodia died in 1797, leaving four sons Ang Chan, Ang Sngoun, Ang Em and Ang Duong. King Rama I considered the princes too young to rule so he did not enthrone a new King of Cambodia until 1806, when the Siamese king eventually allow Ang Chan, eldest son of Ang Eng, to become the new King of Cambodia. However, Ang Chan, given his negative experiences with the Siamese court, became weary of Siamese domination over Cambodia and sought out for Emperor Gia Long of the Vietnamese Nguyen dynasty to counter Siamese influence.^[1] When King Rama I of Siam died in 1809, Ang Chan defied the Siamese right away, refusing to go to attend the funeral of the deceased Siamese king at Bangkok, sending his younger brothers Ang Sngoun and Ang Em to go in his stead. The new Siamese king Rama II made Ang Sngoun and Ang Em the Uprayorach (Second King) and the Ouparach (Third King), respectively, without consulting Ang Chan,^[1] turning Ang Sngoun into a pro-Siamese rival of Ang Chan.

Ang Sngoun, younger brother of the incumbent King Ang Chan of Cambodia, rebelled at Pursat in 1812. The Siamese marched from Battambang into Cambodia to support Ang Sngoun, prompting Ang Chan to flee to take refuge at Saigon under Vietnamese protection.^[1][4] During the flight, Ang Em and Ang Duong, younger brothers of Ang Chan, decided to join the Siamese instead. The Siamese destroyed and burnt down the Cambodian royal capital of Oudong, which stood as the capital of Cambodia for two centuries, in early 1813 and took the three Cambodian princes Ang Sngoun, Ang Em and Ang Duong to live at Wang Chao Khamen^[5] or Cambodian quarters in Bangkok. Emperor Gia Long of Vietnam sent Lê Văn Duyết the Tổng trấn (總鎮) governor of Saigon and Viceroy of Cochinchina to march Ang Chan back to Cambodia in 1813, restoring Ang Chan to rule.^[1] As the royal capital was destroyed by the Siamese, Lê Văn Duyết built a new citadel at Phnom Penh called Banteay Keav for Ang Chan to reside as his capital. In 1814, Gia Long appointed Nguyễn Văn Thoại as bảo hộ^[6] or Protector of Cambodia, essentially the Vietnamese representative minister in Cambodia. The dynastic conflict of 1812–1813 shifted Cambodia from Siamese to Vietnamese domination as Siam lost control over Cambodia to Vietnam but Siam was waiting for the right moment to reclaim its control over Cambodia.

In 1819, Emperor Gia Long initiated a grand construction project of the Vĩnh Tế canal that connected Châu Đốc with Hà Tiên in Southern Vietnam bordering Cambodia. Khmer people were conscripted into the forced hard labor.^[1] Emperor Gia Long died in early 1820, succeeded by his son Minh Mạng. In August 1820, a Cambodian Buddhist monk named Ke declared himself a Neak Sel or holy magician man, rallying Khmer people to rise against Vietnamese domination, leading to the Cambodian Uprising of 1820. Ke and his forced killed the governor of Ba Phnum and established themselves there. The Cambodian king Ang Chan, being under Vietnamese influence, was obliged to send forces under Chauvea Tolaha Tuan Pha (Cambodian Prime Minister of Cham ethnicity) and Samdech Chauponhea Tey to suppress this rebellion. However, Oknha Noren Kol defected to the rebel side and the royal forces were defeated.^[1] Lê Văn Duyết the governor of Saigon sent Nguyễn Văn Trí to bring Vietnamese forces to defeat and kill Ke at Koh Sotin, dissolving Ke's movement. Noren Kol and other followers of Ke were arrested and interrogated. They confessed it was the Cambodian ministers Chauvea Tolaha Tuan Pha and Samdech Tey that had instigated them to aid the rebels in the first place. Tuan Pha, Samdech Tey and Noren Kol were eventually executed.^[1]

In November 1820, King Ang Chan wrote to Lê Văn Duyết at Saigon, asking to resume the joint Cambodian–Vietnamese Vĩnh Tế canal construction project.^[7] 39,000 Southern Vietnamese and 16,000 Khmer men were conscripted to dig the canal day and night. The construction of the Vĩnh Tế canal was eventually finished in 1824. In the same year, King Chan of Cambodia offered three districts of Prey Kabbas (Lợi Kha Bát), Choan Chum (Chân Sum) and Mật Luật and as a personal gift of gratitude to Nguyễn Văn Thoại the Vietnamese Protector of Cambodia. Minh Mạng told Nguyễn Văn Thoại to accept only two districts of Chân Sum and Mật Luật.^[1][7] Nguyễn Văn Thoại died in 1829 and Lê Văn Duyết also died three years later in 1832. Lê Văn Duyết had been the Tổng trấn or powerful Viceroy of Saigon, holding power over Southern Vietnam and Cambodia. Death of Lê Văn Duyết prompted Minh Mạng to enact administrative reforms in 1832 including the abolition of Tổng trấn in favor of Tổng đốc (總督). The Tổng đốc An Hà or governor of An Giang and Hà Tiên provinces would concurrently held the position of bảo hộ or Protector of Cambodia. In late 1832, Lê Đại Cương was appointed as the governor of An Giang and Hà Tiên, also Protector of Cambodia at the same time.^[7]

In 1833, the new officials installed in Southern Vietnam by Emperor Minh Mạng reported that the late viceroy Lê Văn Duyết had been plotting a rebellion. Minh Mạng issued punishments to the associates of Lê Văn Duyết, prompting his adopted son Lê Văn Khôi to kill Minh Mạng's officials and rebelled at Saigon. In 1833, Vietnam was embroiled in three rebellions; Lê Duy Lương Rebellion in Nghệ An province, Le Van Khoi Rebellion at Saigon in the Southern Vietnam in Cochinchina and Nông Văn Vân Rebellion in Cao Bằng province in the Northern Vietnam. Taking advantage of unstable situation in Vietnam, Siam saw an opportunity to reclaim control over Cambodia and possibly to conquer Southern Vietnam.^[4] In November 1833, King Rama III of Siam, with the goal of establishing the pro-Siamese candidates Ang Em and Ang Duong to power in Cambodia and also conquering Saigon, sent Siamese armies to invade Cambodia and Southern Vietnam;

• Chaophraya Bodindecha the Samuha Nayok or Prime Minister of Siam led the Siamese forces of 40,000 men^[8] to invade Cambodia by land from Battambang, going through Cambodia to attack Saigon.
• Chaophraya Phrakhlang, personal name Dit Bunnag, the Minister of Trade, led the Siamese fleet of 10,000 men^[8] from Chanthaburi to attack Hà Tiên by sea, going through the waterways of Mekong Delta to attack Saigon.

Alarmed by Siamese invasion, King Ang Chan of Cambodia dispatched his War Minister Oknha Chakrey Long to defend Cambodia but Chakrey Long could barely raise an army due to manpower shortage,^[1] unable to stop the Siamese at Kampong Chhnang. Ang Chan had to flee from his capital Phnom Penh to take refuge at Long Hồ in Cochinchina. Chaophraya Bodindecha and his Siamese armies marched through Cambodia with ease. Chaophraya Phrakhlang Dit Bunnag attacked Hà Tiên, surprising the Vietnamese, who were unprepared and concentrating on putting down the rebellion at Saigon. Bodindecha assigned Ang Em and Ang Duong to occupy the Cambodian royal capital of Phnom Penh at Banteay Keav. Two Siamese army routes of Bodindecha and Phrakhlang converged at Châu Đốc, where they proceeded downstream the Bassac River, going towards Saigon. However, the Vietnamese Emperor Minh Mạng allocated some troops from Saigon under Nguyễn Xuân, Trương Minh Giảng and Lê Đại Cương to face the invading Siamese.

The Siamese and the Vietnamese fought in the Battle of Vàm Nao in January 1834, in which the Vietnamese prevailed and the Siamese were defeated. The Battle of Vàm Nao turned the tide of war in favor of the Vietnamese. In his retreat, Chaophraya Bodindecha resorted to rounding up as many Khmer people as possible as captives^[1] in order to make up for the Siamese defeat. Bodindecha commanded the Princes Ang Em and Ang Duong to destroy^[1] Banteay Keav, the royal citadel of Phnom Penh. The Siamese suffered further from guerilla attacks of the Cambodians^[4] under Oknha Chakrey Long and Oknha Yomreach Hu, who preyed on the panicked retreating Siamese. Vietnamese commanders Nguyễn Xuân and Trương Minh Giảng and the Cambodian War Minister Chakrey Long pursued the Siamese to the edges of Cambodian territory. By April 1834, the Siamese had all retreated, with Bodindecha retreating to Battambang and Phrakhlang to Chanthaburi.

With the Siamese gone, the refugee king Ang Chan was paraded by the Vietnamese to return to Phnom Penh, where he found his residence, the citadel of Banteay Keav, built by Lê Văn Duyệt for him in 1813, destroyed and burnt down by the Siamese.^[1] Ang Chan built himself a temporary palace at Po Preah Bat, opposite of Phnom Penh on the Bassac River. Ang Chan also promoted his meritorious commanders Chakrey Long and Yomreach Hu to the positions of Chauvea Tolaha (Prime Minister) and Samdech Chauponhea (Deputy Prime Minister), respectively.

Siam's attempt to reassert control over Cambodia in 1833–1834 was a failure, in part due to their geographical unfamiliarity of the Mekong Delta and due to ability of the Vietnamese to allocate some of their troops of Saigon to fend off the Siamese.^[1] Despite Vietnam's victory over the Siamese in Cambodia, Emperor Minh Mạng and the frontline commanders Nguyễn Xuân and Trương Minh Giảng realized the gravity of Siamese military threats and the vulnerability of Cambodian defense. The Vietnamese then decided that reforms and greater authority were needed to safeguard Cambodia and Southern Vietnam from Siamese invasions.

The pro-Vietnamese king Ang Chan of Cambodia, already losing his administrative powers to the Vietnamese,^[1] died in January 1835, leaving the state seal to his Prime Minister Chauvea Tolaha Long, leaving no male heirs but four daughters Ang Pen, Ang Mey, Ang Peou and Ang Sgnoun born to different mothers, leaving the state affairs to Trương Minh Giảng and Lê Đại Cương. The Vietnamese seized the opportunity at the death of Ang Chan to assert more control over Cambodia.^[2] As the surviving male candidates, the Princes Ang Em and Ang Duong, were with the Siamese at Battambang, Minh Mạng and Trương Minh Giảng had to choose among four daughters of Ang Chan the new ruler of Cambodia. The eldest daughter was Princess Ang Pen or Ang Ben but her mother was Neak Neang Tep, daughter of Chaophraya Aphaiphubet Baen the first Siam-appointed governor of Battambang^[1] so Ang Pen was passed over due to her strong connection with Siam.

The Vietnamese built a new citadel at Phnom Penh called Trấn Tây (鎮西) in April 1835^[7] to replace the Banteay Keav citadel that had been destroyed by the Siamese, also to serve as the center of Vietnamese administration in Cambodia.

The choice fell upon the second daughter Princess Ang Mey, who was enthroned as the Queen Regnant of Cambodia, granted the Vietnamese title Quận chúa^[9] (郡主), becoming the only historical female ruler of Cambodia.^[10] Other three princesses were granted the inferior title of Huyện quân^[9] (縣君). Minh Mạng sent a Vietnamese imperial representative to perform the investiture ceremony on Queen Ang Mey and her sisters, during which the queen, the princesses, the Cambodian ministers and officials, all dressed in Vietnamese costumes, kneeled down in front of Minh Mạng's edict and performed Five Obeisances^[1] in Vietnamese rather than Cambodian rituals.^[11]

In November 1835, Emperor Minh Mạng officially established Trấn Tây Thành^[12] (鎮西城) or Trấn Tây Province (lit. Western Commandery)^[2][13] over Cambodia, appointing Trương Minh Giảng as Trấn Tây tướng quân^[7] (鎮西將軍) or Governor-General of Trấn Tây and Lê Đại Cương as Tham tán Đại thần^[7] or counselor. The government of Trấn Tây Province spread along the existing Cambodian administrative network, with the central government at Trấn Tây in Phnom Penh. Trấn Tây's central government at Phnom Penh composed of the Tướng quân (將軍) or Governor-General, his counselor called Tham tán Đại thần (參贊大臣), and a Đề Đốc (提督) military commander. Regionally, Cambodia srok districts were supplanted with thirty-three Vietnamese districts or phủ (府), which were given Sino-Vietnamese^[13] names with Governors or Tuyên phủ (宣撫) installed at three important regional towns; Kampong Thom (Hải Đông, 海東), Pursat (Hải Tây, 海西) and Sambok (Sơn Phủ).^[7] Kampot (Quảng Biên) and Kampong Saom (Khai Biên) were incorporated into Vietnam's Hà Tiên province. Districts were administered by the Vietnamese governors, seconded by Cambodian Oknha.^[1]

Cambodian officials were left with reduced powers with actual administration in the hands of the Vietnamese, who introduced Sinitic bureaucracy as a government reform. Personnel appointment, salary distribution, military affairs and rice granary were controlled by the Vietnamese.^[13] Even though the Vietnamese dominated central governance and the three regional outposts, the Cambodians were still left with much role in regional administration and labor mobilization^[13] but appointment of Cambodian officials was controlled by the Vietnamese. Cambodian officials were given Sino-Vietnamese bureaucratic titles.^[14]

As Cambodia, like Siam, had no standing army^[12] as the untrained conscripts were levied during wars, Minh Mạng sought to arm Cambodia militarily^[13] to defend against Siamese invasions. Trương Minh Giảng took over the Cambodian military, establishing new hierarchy and training units throughout Cambodia. Trương Minh Giảng brought 5,000 Vietnamese military men to Phnom Penh to occupy Cambodia.^[1] Proportion of ethnicities of military personnel was one Vietnamese per four enlisted Cambodians.^[1] The Trấn Tây regime also sought to quantify and systematize landholdings and taxation.^[13] Trương Minh Giảng was additionally made the governor of An Giang and Hà Tiên provinces (Tổng đốc An Hà)^[7] in September 1836, giving Trương Minh Giảng an unparalleled power and influence over Cambodia and Cochinchina.

Apart from the Sino-Vietnamese bureaucracy that was introduced as a government reform into Cambodia, Minh Mạng also pioneered the 'civilizing mission' of Cambodia. Minh Mạng, himself a staunch Confucian, saw Khmer culture as hindrance to effective governance and viewed that the Confucian bureaucracy should be the better alternative, as Minh Mạng told Trương Minh Giảng; "The barbarians have become my children now, and you should help them, and teach them our customs."^[11][13] and, according to Trương Minh Giảng; "Cambodian officials only know how to bribe and be bribed.".^[12] Minh Mạng justified his annexation of Cambodia on the 'superior Confucian' Vietnamese cultural grounds^[13] as his civilisatrice mission on Cambodia and Khmer people called cải thổ qui lưu^[14] (改土歸流) or "changing natives to officials'. In 1834, Minh Mạng sent a secret edict to Vietnamese officials in Cambodia to gradually replace indigenous Khmer culture with Vietnamese culture,^[15] which was to be accomplished by Vietnamese 'colonization'^[13] of Cambodia. Minh Mạng sent Southern Vietnamese landless peasants, crime convicts and the Chinese of Southern Vietnam into Cambodia.^[12][15] Around 5,000 Vietnamese people moved into Cambodia each year.^[1]

According to a Thai record, Chauvea Tolaha Long the Cambodian Prime Minister spoke to Trương Minh Giảng in Vietnamese language. Given two decades of Vietnamese domination, the Cambodian ministers seemed to speak Vietnamese to their Vietnamese overseers. Cambodia and Vietnam, however, belonged to totally different cultural spheres, where Indosphere borders Sinosphere, one of the most sharply-defined in nineteenth-century Asia.^[13] A Vietnamese writer took a disdain on Cambodian cultural practices including wearing Chong Kben loincloths, eating with fingers and prostration in the presence of dignitaries,^[13] the norms that they shared with other Theravadin cultures including the Siamese. The Trấn Tây authority ordered the Khmer people to wear trousers instead of skirts, to wear hair long instead of short-cropped^[13] and to adopt Vietnamese cultural practices, including costume, rituals and hairstyle.^[15] Giảng also demanded that Cambodian ministers, including Tolaha Long, dress in Vietnamese official costume and pay respect to him every morning.^[1] When having audiences with their Vietnamese superiors, the Cambodian officials were to adorned themselves with Vietnamese costume, wearing Vietnamese Khăn vấn turban. Thai chronicles mockingly called the Khmers adopting Vietnamese culture the "New Vietnamese".^[13]

Cambodia, like Laos and Siam, had been underpopulated. The land was abundant but the people were few. There was few labor force to clear the forests and to grow crops nor there were incentives for land development and urbanization in traditional Southeast Asian Theravadin cultural sphere, in which subsistence rather than development-driven economy thrived. The Vietnamese found Cambodia to be lacking in agriculture,^[12] being mostly in jungles, which the Vietnamese considered wasted opportunities. According to Minh Mạng, about Cambodia; "the land is plentiful and fertile, and that there are plenty of oxen but the people had no knowledge of agriculture, using picks and hoes, rather than oxen. They grow enough rice for two meals a day, but they don't store any surplus.".^[12][13] A Vietnamese official reported that only thirty to forty percent of Cambodian lands were cultivated.^[12] The Vietnamese then pioneered intensive agricultural development in Cambodia, in which the Khmers were conscripted for corvée labor, plantations and forest cutting.^[1] The Vietnamese also took over Cambodia economically. Cambodian marketplaces were filled with Vietnamese merchants.^[1]

Two years into the establishment of Trấn Tây regime, Khmer people began to feel the effect of limitless authority of Vietnamese commissioners. In 1837, Trương Minh Giảng came up with a construction project of a long road connecting Trấn Tây or Phnom Penh to the Southern Cambodian town of Treang and eventually ending at Hà Tiên in Cochinchina with outposts built along the road at every two kilometers to facilitate communications between Cambodia and Southern Vietnam. Khmer men were conscripted to construct this grand construction project, reminiscent of when Khmer people were conscripted to dig Vĩnh Tế Canal that connected Châu Đốc and Hà Tiên – the discontent that led to a major Cambodian uprising against Vietnam in 1820.^[15] This Vietnamese-pioneered construction project seemed to offend the Oknhas of Southern Cambodia.

In the same year, two Cambodian Oknhas from Kampong Saom (a Cambodian port town in Southwestern Cambodia on the coast of Gulf of Siam, Vietnamese name Khai Biên, then part of the Vietnamese Hà Tiên province) called Oknha Chey and Oknha Chu,^[16] who were brothers, took up arms and rallied the Khmers against the Vietnamese rule. Trương Minh Giảng quickly sent Khmer-Vietnamese forces to put down this rebellion.^[16] Oknha Chey and Oknha Chu fled to Siam.

The first serious challenge to the rule of Trấn Tây regime sprang up in Kampong Svay–Kampong Thom or Hải Đông district. Kampong Svay was one of the five major regional towns of Cambodia. Cambodian governors of Kampong Svay held the title Oknha Dechou.^[1] Kampong Svay held jurisdiction over the area generally to the east of Tonle Sap Lake, spanning from Baray to Stoung, which bordered the Siamese-controlled Siemreap district via Chikraeng. In the Trấn Tây administration, the Vietnamese established their headquarter at Kampong Thom, which they called Hải Đông, about fifteen kilometers to the southeast of Kampong Svay, locating on the Steung Saen River. Kampong Thom or Hải Đông was considered one of the three important regional towns so a Vietnamese governor Tuyên phủ was appointed to Kampong Thom.

Cambodian monk named Pich, recounting his experiences in his writing Raba Ksatr Pheanday Udai Raja Eng Chant (1855)^[17] or "History of the Reign of King Outey Reachea Ang Chan", narrated that the Khmers of Kampong Svay district were subjected to intensive labor works including digging earth, building fortresses, rice cultivation and rice transportation.^[12] Pich stated that even the Cambodian officials of Kampong Svay had to manually do the labors themselves ^[12] but no one dared to speak up because they feared the Vietnamese authorities

In 1837, an Oknha Decho named Ream^[16] rebelled in Kampong Svay against the Trấn Tây regime. Trương Minh Giảng against sent forces to suppress this rebellion, capturing Oknha Decho Ream to be executed at Phnom Penh. Trương Minh Giảng then appointed Oknha Chap as the new Oknha Decho governor of Kampong Svay. Giảng also appointed a new Tuyên phủ and a Cambodian official named Snang Ey^[16] (Đô Y)^[7] with the Vietnamese position of Chánh lãnh binh to Kampong Thom.

Oknha Chey and Oknha Chu of Kampong Saom (Khai Biên), who had earlier escaped to Siam in 1837, returned to Kampong Saom and instigated a Cambodian official in Kampong Saom named Di,^[7] who was holding the Vietnamese position of An Phủ of Khai Biên to rebel against the Vietnamese in February 1838.^[7] This Cambodian uprising at Kampong Saom was eventually subdued by the Vietnamese authorities of Hà Tiên province.

Also in February 1838,^[7] Snang Ey arose against Vietnamese rule. Snang Ey murdered the Vietnamese Tuyên phủ of Kampong Thom and rallied 1,000^[7] Khmer men from Kampong Svay district to rise up to massacre the Vietnamese in this whole district, from Baray to Stoung.^[12] Trương Minh Giảng was infuriated and embarrassed when this incident was reported to the Emperor Minh Mạng, albeit in softer narrative. As the result of this mishap, Lê Đại Cương was dismissed from his Tham tán Đại thần counselor position, sent to a military garrison at Kampong Thom, eventually sent to be imprisoned.^[7] Lê Đại Cương was replaced by Dương Văn Phong as the counselor of Trấn Tây.

Trương Minh Giảng sent out Cambodian–Vietnamese forces under Đoàn Văn Phú and Chauvea Tolaha Long the Cambodian Prime Minister from Phnom Penh to put down the Kampong Svay rebellion. The fighting continued into March, when the Trấn Tây and the rebels clashed at Steung Trang and Kampong Siem^[7] on the Mekong. Snang Ey and his irregulars could not stand against the professionally-trained Vietnamese forces from the capital. Snang Ey and his allies fled north across the Tonle Repou River into the Siam-controlled Lao Champasak kingdom, taking with him the majority of Khmer inhabitants of Stoung and Chikreang.

With Snang Ey repelled, Trương Minh Giảng conducted a violent purge on the Cambodian officialdom of Kampong Svay. Giảng ordered the arrest of all Cambodian officials in Kampong Svay,^[12] subjecting them to punishments and executions. Oknha Decho Chap the governor of Kampong Svay, who seemed not involved with Snang Ey, was imprisoned in a cage, burnt alive, dismembered and eliminated.^[12] Other Cambodian officials of Kampong Svay were executed at Phnom Penh. Those who were spared were sent to Vietnam for further interrogations.

During the first years of the Trấn Tây regime, the Vietnamese Emperor Minh Mạng took a paternalistic and gradualist approach towards integration of Cambodia into Vietnam.^[12] After the Cambodian uprisings at Kampong Svay and Kampong Saom from 1837 to early 1838, the Cambodian insurgencies cooled down but Minh Mạng and Trương Minh Giảng took a harder, less reconciliatory stance. In 1838, Minh Mạng complained that the Cambodians disregarded his generosity in spite of his best intentions; "Imperial troops were dispatched to Cambodia, costing millions of coins, and brought you security by destroying the Siamese. Troops were stationed to bring peace, like bringing the Khmer people out of the mud into a warm feather bed. Why are there people who hate us and believe the rebels?"^[12] The six-year period of Vietnamese rule over Cambodia would not be remembered by elegant Confucian-style institutional and cultural reforms but rather by persistent subjugation of Khmer people to labors and hardships and the threat to Khmer identity,^[13] becoming the nadir of Post-Angkor Cambodian history.^[2]

Administration of the Trấn Tây government in Cambodia required officials trained in Confucian statecraft, which were not locally produced in Cambodia but rather imported from Vietnam. Earlier in 1835, low-ranking mandarins and secretaries from Huế^[14] were imported into Cambodia to work in the Trấn Tây administration. Later in that year, ten Vietnamese provincial educational ministers and sixty-eight low-ranking provincial officials were sent into Cambodia. The educational ministers were to teach Vietnamese language to the Khmers.^[14] However, shortage of officials trained in Sino-Vietnamese bureaucracy was a persisting problem, as the Trấn Tây government took tighter grip over Cambodia. In October 1838, Minh Mạng encouraged Vietnamese scholars and officials in Central Vietnam from Quảng Bình to Bình Thuận to go to Cambodia to take official positions.^[7]

Next year, in 1839, Minh Mạng was upset to learn that the Cambodian ministers and officials still stuck with the usage of their traditional Cambodian noble titles like Oknha instead of the Vietnamese titles like Huyện uý, Phủ uý, Quản cơ or Phó quản bestowed upon them; "in correspondence and conversation they still use Cambodian titles. The Cambodians should be told that it is an honor to have titles bestowed upon them by our court. In conversations, therefore, they should use our titles rather than theirs."^[12][13] Trương Minh Giảng even came up with the idea of abolishing Cambodian aristocratic titles altogether. Trương Minh Giảng proposed to replace the chauvay srok or Cambodian Oknha town governors with Vietnamese governors, starting with the srok surrounding Trấn Tây or Phnom Penh first.^[1][13]

When King Rama I of Siam sent the Cambodian king Ang Eng out to rule Cambodia in person in 1794, Siam annexed Northwestern Cambodia including Battambang and Siemreap^[4] and gave it to Chaophraya Aphaiphubet Baen the first Siam-appointed governor of Battambang to govern. Siam had been in control of Northwestern Cambodia through the Siam-appointed governors of Battambang since then. In 1834, when Chaophraya Bodindecha and the Siamese had retreated from Cambodia to Battambang, King Rama III of Siam made Prince Ang Em the governor of Battambang.^[18] Ros, son of Chaophraya Aphaiphubet Baen, was appointed as Phraya Palat the vice-governor of Battambang under Ang Em. Prince Ang Duong, younger brother of Ang Em, was made by Siam as governor of Mongkolborey. Though defeated, the Siamese remained vigilant and made extensive preparations for prospective reassertion of Siamese influence over Cambodia. Chaophraya Bodindecha built a new Battambang fortress in February 1837 and Siemreap was fortified in 1839.^[8] In April 1837, Bodindecha went to Khukhan and made extensive manpower survey of Northern Khmer towns in order to enlist Northern Khmer people into future wars with Cambodia–Vietnam.^[8] Coincidental or not, Bodindecha's stay at Battambang and Khukhan happened in the same time as the devastating Snang Ey's rebellion in Kampong Svay.

The Siamese allowed Northwestern Cambodia to retain most of its Khmer ethnic identity and culture, never pursuing assimilation policies like the Vietnamese. The Siamese government of Battambang was filled mostly with Cambodian officials working under Siam. There was no need to assimilate nor integrate Northwestern Cambodia as the Cambodians and the Siamese already had similar cultures, both belonging to the same Southeast Asian Theravadin cultural sphere. Governance and bureaucracy of Cambodia and Siam were similar^[14] with cognate rank and title names, for example; Oknha vs Phraya, Yomreach vs Yommarat, Chakrey vs Chakri, Kralahom vs Kalahom, etc. However, these Cambodian ministerial positions did not exist in Battambang because they could only be appointed by the ruler of Cambodia. The government of Battambang and Siemreap were treated as a Siamese provincial administration.

The Siamese demanded cardamom tributes^[18] that involved conscripting local Khmer and Chong people to gather cardamoms from the Cardamom Mountains.^[18] The Siamese court at Bangkok would then sell the cardamoms gathered from Battambang to Chinese merchants at high prices^[18] to earn revenue. The Siamese also mobilized Northwestern Cambodian people for warfare and constructions.^[18] In April 1837, Chaophraya Bodindecha conscripted local Khmer men to construct the new Battambang city, moving from its previous site at Baset to the present-day site on the Sangkae River.^[19] When Jens Westengard the American advisor to King Chulalongkorn conducted a survey of Northwestern Cambodia, known as Monthon Burapha, in 1904, he found out that the region was overwhelmingly Cambodian, with only 2,000 Thai people out of 300,000 inhabitants of the region, despite 112 years of Siamese rule.

In 1827, Phraya Aphaiphubet Ros the Siam-appointed governor of Battambang was accused by his deputy Chet of incompetence, resulting in the dismissal of Ros from the governorship of Battambang.^[18] Chet replaced Ros as Phraya Aphaiphubet the governor of Battambang and Chet's son Som was appointed Phra Phithakbodin, an official in Battambang. Phraya Aphaiphubet Chet accompanied Chaophraya Bodindecha on the Siamese invasion of Cambodia in 1833 and when Chet returned to Battambang in 1834, he died. King Rama III and Bodindecha decided to make the Cambodian prince Ang Em, the Siam-sponsored pretender to the Cambodian throne, the governor of Battambang in order for Ang Em to rally supports from Khmer people. Ros, the former governor of Battambang, who was dismissed in 1827, was reinstated as Phraya Palat the vice-governor of Battambang under Ang Em. Meanwhile, Prince Ang Duong was appointed the governor of Mongkolborey, another town in northwestern Cambodia.

When the pro-Vietnamese King Ang Chan of Cambodia died in 1835, Ang Duong sent a letter to Trương Minh Giảng at Phnom Penh, saying that he had been detained by the Siamese and urging the Vietnamese to rescue him and make him King of Cambodia. Trương Minh Giảng did not believe Ang Duong, considering it a Siamese deception.^[7]

Lack of male Cambodian royalty was a disadvantage of the Vietnamese in procuring support from the Cambodian Oknhas. Perhaps having a traditional legitimate male Cambodian king under Vietnamese influence would persuade the Cambodians to acquiesce to Vietnamese rule, like during the reign of Ang Chan. Trương Minh Giảng then devised a plan to make Prince Ang Em defect to Vietnamese side. Around 1837, according to Cambodian and Thai chronicles, Trương Minh Giảng sent a Vietnamese man who used to take care of Ang Em when he was young to bear a secret letter from Giảng to Ang Em at Battambang, urging Ang Em to defect to Vietnam, promising to make Ang Em the rightful King of Cambodia.^[1] However, Ang Em was in no position to do anything as the powerful Siamese general Bodindecha still had much presence.

Secret communications between Ang Em and Trương Minh Giảng led to a fallout between the princely brothers Ang Em and Ang Duong. Chauvea Tolala Long the Prime Minister of Cambodia, knowing that the Vietnamese Governor-General had made a confidential contact with Ang Em, Tolaha Long made his own bid by sending a secret letter to Ang Duong at Mongkolborey, urging Ang Duong to defect to Cambodia. Internal politics of Battambang also came into play. Phraya Palat Ros had previously been dismissed from government by instigation of Chet, while Phra Phithakbodin Som was a son of Chet. Phraya Palat Ros then took the side of Ang Em, while Phra Phithakbodin took the side of Ang Duong. Cambodian chronicles stated that Ang Duong was framed by Ang Em^[1] but Thai chronicles told a different story; it was Tolaha Long who persuaded Ang Duong to mutiny against Siam.^[8] Bodindecha and the Siamese were completely unaware of these secret political endeavors.

Departure of Chaophraya Bodindecha to Bangkok in 1838 put Battambang in political struggles. Ang Duong and Phra Phithakbodin Som planned a coup in Battambang in November 1838. The Siam-appointed governor of Moung Ruessei was to march military forces from Moung Ruessei to seize Battambang for Ang Duong.^[8] However, the plan leaked to Ang Em's faction. Unusual military march from Moung Ruessei towards Battambang confirmed the suspicion. Phraya Palat Ros reported this impending rebellion in Battambang to Bangkok in November 1838, on behalf of Ang Em, leading to the arrest of Prince Ang Duong, Phra Phithakbodin and their accomplices to Bangkok. Ang Duong was imprisoned but was later released and put under house arrest instead.^[8] King Rama III of Siam decided not to punish Phra Phithakbodin Som and his associates for the sake of political peace in Battambang and released Phithakbodin and other conspirators of Ang Duong's plot to return to Battambang. Ang Em the governor of Battambang assigned Phithakbodin as a border patrol at Moung Reussei.

After Ang Duong's abortive plot, one year later, it was Ang Em's turn to arise. Taking advantage of absence of Bodindecha in Battambang, on 24 December 1839, Cambodian Prince Ang Em, being the Siam-sponsored candidate for about twenty years since the death of his elder brother Prince Ang Sngoun in 1816, disappointed by Siamese failures to put him on the Cambodian throne,^[1] becoming a mere Battambang governor, mutinied against Siam and seized power in Battambang. Ang Em reportedly held two swords in his two hands^[8] and led his forces to storm the residence of Phraya Palat Ros the vice-governor of Battambang. Ang Em's forces shot dead a door guard and a concubine of Palat Ros. Phraya Palat Ros put up a gun to fight but his wife urged him to stop resisting or else their whole family would be killed.^[8] Palat Ros surrendered as Ang Em captured Cambodian–Siamese officials of Battambang and forced around 5,000 to 6,000^[8] inhabitants of Battambang to leave the city, going to join the Vietnamese. French missionary Jean-Claude Miche, who happened to be in Battambang during this event, told that, in the night of December 24, 800 barges carried off around 8,000 to 10,000 souls to leave Battambang to follow Ang Em (called Neac Ang Em by Miche). By the morning on Christmas, December 25, Battambang became a deserted evacuated city, with only an ailing old woman and a drunkard man remaining.

In January 1840, Prince Ang Em (called Nặc Yêm in Vietnamese), along with his entourage, his captured Battambang officials including Phraya Palat Ros (Ba Lặc Đột)^[7] and the inhabitants of Battambang, traveled by the Tonle Sap Lake and reached the Vietnamese-controlled Pursat. The Vietnamese Đề Đốc commander at Pursat Võ Đức Trung reported to Trương Minh Giảng at Phnom Penh, who then reported to the Vietnamese Emperor Minh Mạng at Huế.^[7] Unlike Trương Minh Giảng, Minh Mạng had no intentions of raising Ang Em to be the Cambodian king, saying that Ang Em's crimes were unforgivable.^[1] Minh Mạng ordered Ang Em detained and ordered Phraya Palat Ros, the Siamese leader, to be transferred to Huế in chains for interrogations. Followers and servants of Prince Ang Em were deported to be resettled in Saigon, Long Hồ and Đồng Nai in Southern Vietnam.^[7] The Cambodian inhabitants of Battambang coming with Ang Em were distributed to be resettled in the towns of the Pursat or Hải Tây district including Krakor, Krang, Baribour and Kampong Chhnang. Ang Em and Palat Ros were taken to Trấn Tây or Phnom Penh in January 1840.

Chaophraya Bodindecha was greatly alarmed by the news of developments in Battambang and hurriedly took off from Bangkok with Siamese armies January 1840 to Battambang. At Battambang, Bodindecha conducted a survey on the losses. He found out that Ang Em had taken with him 181 officialdom families, 503 families of inhabitants of Battambang and also 319 families of inhabitants of Moung Ruessei.^[8] 119 families and some officials remained in Battambang. Bodindecha made Phra Phitakbodin Som (conspirator of Ang Duong's plot) the interim governor of Battambang. Phra Narinyotha Nong was made the interim Palat or vice-governor of Battambang.

Defection of Ang Em, who had taken virtually all the manpower and resources with him to join Vietnam, had a devastating effect for the Siamese. Battambang, serving as the buffer zone^[4] between Central Siam and Cambodia since the late eighteenth century, was then completely exposed. Cambodian or Vietnamese invasion could happen anytime. Northern Khmer troops of 4,300 men^[8] conscripted from Khukhan, Surin, Sankha and Sisaket arrived in Battambang but Bodindecha could not station them in Battambang due to food shortage so he had to send these Northern Khmer men out to guard Battambang while Bodindecha himself would rehabilitate Battambang;

• Phraya Ratchanikun, personal name Suea, led Northern Khmer forces to guard and defend Siemreap
• Phra Phromborrirak, personal name Kaew, a son of Bodindecha, led Northern Khmer forces to guard Muong Ruessei
• Phra Phirenthorathep, personal name Kham, formerly known as Phra Ratchawarin, who had led the Siamese forces to attack Vietnamese Trấn Ninh or Muang Phuan in 1834, led forces to guard Kampong Preah just about fifteen kilometers to the southeast of Battambang.

Minh Mạng ordered executions of ten Battambang officials at Phnom Penh, whereas Ang Em and Palat Ros were sent to Huế. Phraya Palat Ros was executed at Huế, while Ang Em was imprisoned. Neak Neang Ros, mother of Ang Em and Ang Duong, whom Ang Em had taken with him from Battambang, was put under house arrest in Saigon. Ang Phim, son of Ang Em, was also imprisoned in Saigon. Minh Mạng has no intentions of restoring the Cambodian monarchy. His goal was to integrate Cambodia politically and culturally into Vietnam.^[12][13]

Minh Mạng saw Siam as being on high alert after the defection of Ang Em but Siam was also in a weakened state due to the loss of manpower in Battambang. As the Siamese would soon march into Cambodia again in order to pursue Ang Em, Minh Mạng decided that he should strike first. However, the Vietnamese should not directly attack Battambang or else it would lead to a major Siamese–Vietnamese War. It should be the Cambodian leaders who marched to attack Battambang, which would be treated as a Cambodian internal conflict.^[1] Ang Chan had long coveted for the recovery of northwestern Cambodia taken from his father Ang Eng by Siam in 1794, which he did not accomplish before his death in 1835. This was the best time for the Cambodia to reclaim the area.^[1] Trương Minh Giảng told the top three Cambodian ministers Chauvea Tolaha Long the Prime Minister, Samdech Chauponhea Hu the Deputy Prime Minister and Oknha Kralahom Kinh to bring Cambodian forces to attack and reclaim Battambang. The three Cambodian ministers, however, refused on the grounds that the Siamese had already been vigilant after Ang Em's defection and their chance of victory was low.^[1]

The Vietnamese Emperor Minh Mạng welcomed the incoming Cambodians from Battambang with delight. In February 1840, Minh Mạng decreed that the newly arrived Cambodians classified as Tân dân (新民) or New Subjects.^[7][15] Minh Mạng also ordered the Trấn Tây administration to register these new subjects, give them Vietnamese surnames and exempt them from taxation and labor.^[7] Also in early 1840, Minh Mạng commanded Trấn Tây to conduct a complete survey of available manpower in Cambodia.^[1] Trương Minh Giảng proposed a reform of provincial division of Trấn Tây Cambodia, which was re-arranged into ten districts or phủ (府), each with a number of huyện (縣) or sub-districts, each of them given Sino-Vietnamese names.^[1] Four districts near the capital were put under direct jurisdiction of the central Trấn Tây government. The governors or Tuyên phủ of Hải Tây (Pursat) Hải Đông (Kampong Thom) and Sơn Tĩnh (Sambok) were given two districts each. The census revealed available manpower of 40,000 men in Trấn Tây Cambodia.^[1]

In March 1840, Dương Văn Phong the Tham tán Đại thần or counselor took the top three Cambodian ministers Chauvea Tolaha Long (Trà Long), Samdech Chauponhea Hu (Nhâm Vu) and Oknha Kralahom Kinh (La Kiên) to visit the Vietnamese Emperor Minh Mạng at Huế. Minh Mạng gave the three Cambodian ministers rewards and ranks in return.^[7]

With total annexation of Cambodia in mind, Minh Mạng decided to make the Cambodian royalty obsolete. In June 1840, Minh Mạng demoted the title of Queen Ang Mey of Cambodia from Queen of Cambodia (Chân Lạp quận chúa) to Princess of Mỹ Lâm (Mỹ Lâm quận chúa).^[1][7] Her sisters the three princesses, Ang Pen, Ang Peou and Ang Sngoun also had their titles demoted.

As Minh Mạng took a tighter grip on Cambodia, he appointed more commissioners to Trấn Tây. In July 1840, he appointed Lê Văn Đức to be the Khâm sai đại thần^[7] (欽差大臣) or Imperial Envoy to Trấn Tây Cambodia. In the Trấn Tây government, there was Trương Minh Giảng who was the Tướng quân or Governor-General, Dương Văn Phong who was the Tham tán Đại thần or counselor and Lê Văn Đức who was the Khâm sai đại thần or imperial envoy from the capital.

When Minh Mạng discovered that the Cambodians underreported the number of available manpower in Cambodia by 15,000 men, he put the guilty on the top three Cambodian ministers at Huế. In July 1840, Minh Mạng demoted the three Cambodian ministers Chauvea Tolaha Long, Samdech Chauponhea Hu and Oknha Kralahom Kinh and exiled them to Northern Vietnam. Chauvea Tolaha Long was exiled to Hanoi. Samdech Chauponhea Hu was exiled to Bắc Ninh and Oknha Kralahom Kinh to Hưng Yên.^[7]

When the Banteay Keav citadel of Phnom Penh, which contained the royal palace of King Ang Chan, was destroyed and burnt down by the Siamese in 1834, Ang Chan had not yet built himself a new palace or capital. Ang Chan instead built a temporary palace opposite of Phnom Penh on the Bassac River at Po Preah Bat, also called Slaket (La Kết). Ang Chan lived at Po Preah Bat for ten months until his death in January 1835. The Vietnamese built a new citadel called Trấn Tây at Phnom Penh in April 1835^[7] but daughters of Ang Chan; Ang Pen (Ngọc Bợn), Ang Mey (Ngọc Vân, Queen Regnant), Ang Peou (Ngọc Thu) and Ang Sngoun (Ngọc Nguyên) resided at Po Preah Bat palace of their father, not entering Trấn Tây the citadel. Queen Ang Mey and her sisters were powerless figureheads without any actual administrative powers, which laid in the hands of the Vietnamese and Trương Minh Giảng. According to Thai chronicles, Minh Mạng proposed to marry one of his sons to Ang Mey but faced strong opposition from Cambodian Oknhas.^[8]

Neak Neang Tep, a consort of the deceased king Ang Chan and her brother Preah Angkev Ma lived at Battambang. Both Tep and Ma are children of Chaophraya Aphaiphubet Baen, the first Siam-appointed governor of Battambang. Tep was the mother of Princess Ang Pen, the eldest daughter of Ang Chan and elder sister of Queen Ang Mey. When Ang Em rebelled against Siam at Battambang and deported the inhabitants in December 1839, Tep and Ma did not go with Ang Em but stayed in Battambang. Ma sent his younger brother named Mao to go with Ang Em to Phnom Penh, pretending to join the prince's entourage. Mao then delivered a secret letter to Princess Ang Pen at Po Preah Bat. Her uncle, Preah Angkev Ma, wrote to Ang Pen, urging her to flee from Phnom Penh to join her mother in Battambang.^[8][7] The plan to take Ang Pen to Battambang was oversaw by the Cambodian minister Samdech Chauponhea Hu.

In July 1840, Dương Quan Thảo,^[7] a spy of Trương Minh Giảng in Pursat, discovered the plot to move Ang Pen to Battambang and informed the Governor-General at Phnom Penh. Trương Minh Giảng conducted the investigation, discovered the plot and arrested Mao in Phnom Penh. Trương Minh Giảng reported this incident to Minh Mạng at Huế. The Vietnamese Emperor was furious as this was his last straw. This incident completely destroyed Minh Mạng's trust on the Cambodian royalty. Minh Mạng commanded Trương Minh Giảng to charge Ang Pen and Mao with sedition. Lê Văn Đức the new imperial investigator arrived in Phnom Penh on 14 August 1840.^[20] On the same day, Trương Minh Giảng and Lê Văn Đức issued sweeping reforms in Trấn Tây Cambodia. Vietnamese Tri phủ governors were installed in all Cambodian towns, reducing the roles of Cambodian Oknhas. The Trấn Tây government seized all Cambodian administrative seals from Cambodian officials, who were given Vietnamese-style seals instead. The Cambodian Oknhas complained that their new Vietnamese seals did not indicate rank,^[13] disregarding traditional Cambodian rank system. Trương Minh Giảng also command all the Cambodian Oknhas to visit Emperor Minh Mạng at Huế but no one dared to go as the three Cambodian top ministers had not yet returned, fearing that they would be killed or detained.

On the fateful evening of 23 August 1840,^[20] Trương Minh Giảng held a celebration banquet for the newly-arrived Lê Văn Đức at his residence in the Trấn Tây citadel in Phnom Penh, which all the Cambodian Oknhas and the four Vietnamese princesses were compelled to attend. Trương Minh Giảng also had his men surround the place. In front of the whole audience, Giảng made a shocking declaration that Princess Ang Pen had been in sedition, planning to escape to Battambang to join her mother and her uncle with the help of her another uncle named Mao. Giảng declared that Ang Pen would be held for trial and three other princesses Ang Mey, Ang Peou and Ang Sngoun were to be exiled to Saigon. This event shocked the Cambodian nobles, who saw their royalty helplessly punished and exiled by the Vietnamese. Next day, on August 24,^[20] the three princesses were sent away from Phnom Penh. As Somdech Chauponhea Hu, who had already been in exile in Bắc Ninh, was implicated in Ang Pen's plot so his son, his wife, his brother Oknha Reachea Sneha the governor of Sambok and his friend Oknha Montrey Sneha the governor of Kampong Siem were all arrested.

Princess Ang Pen was found guilty of sedition against Vietnam but the Vietnamese could not execute her in Cambodia lest the Cambodians would arise. In August 1840, Ang Pen was secretly carried off to Long Hồ in Southern Vietnam, where she was executed by drowning in the Mekong.^[9] Execution of Ang Pen was conducted in utmost secrecy. The Cambodians did not know about her fate until much later. Three other princesses; Ang Mey, Ang Peou and Ang Sngoun, were exiled to Saigon, where they were given rice and money as yearly stipend.^[1]

The Cambodians were upset and angered by Vietnam's treatment of their royalty, whose fate were unknown to them. Even though the Cambodian Queen Regnant Ang Mey had no actual powers, she had essential ceremonial role of conferring titles, honors and dignity on the Cambodian Oknha nobles.^[13] Without the royalty, the root of Cambodian nobility would be threatened^[13] as there would be no one to affirm the ranks and honors of the Oknhas. For the Vietnamese, the Cambodian princesses were mere officials under Emperor Minh Mạng but for the Cambodians they were sacred royalty. General resentment of Khmer people for Vietnamese policies in Trấn Tây Cambodia including forced labors and ethnocultural assimilation attempts, combined with Vietnamese punishments of the Khmer princesses, incurred the Khmers to arise against the Vietnamese rule.^[1] The Cambodians viewed the Vietnamese as extinguishing Cambodian monarchy, Theravada Buddhism and traditional Khmer institutions.^[13] Vietnamese policies in Cambodia, regardless of intentions, struck at the foundation of Cambodian identity.^[13] According to Cambodian and Thai chronicles, the Vietnamese dismantled Theravadin temples for bricks to construct fortresses, melted down Buddha statues to cast bronze bullets and even cut down Bodhi trees.

On 3 September 1840,^[20] Oknha Outey Thireach Hing the Cambodian governor of Samraong Tong (forty kilometers to the southwest of Phnom Penh) fled into the jungles to insurrect against the Trấn Tây government. To prevent the local Khmer population to follow suit, Trương Minh Giảng sent pro-Vietnamese Cambodian official Oknha Srei Thommea Thireach to take control of Samraong Tong. Four days later, on September 7,^[20] Oknha Vongsa Anchit Mey the governor of Bati (thirty kilometers to the south of Phnom Penh) also fled into the jungles to revolt. Trương Minh Giảng sent Oknha Akkareach Prom to pacify Bati but Oknha Akkareach instead joined Oknha Mey in rebellion against the Trấn Tây regime.

On 8 September 1840,^[20] the Trấn Tây citadel sent out Cambodian–Vietnamese forces to put down the insurrection of Oknha Vongsa Anchit Mey of Bati. The Trấn Tây forces and the rebel forces clashed at Preak Touch to the south of Phnom Penh, during which the rebels prevailed. Oknha Akkareach Prom would later wrote to the Siamese supreme commander Chaophraya Bodindecha that "We are happy killing the Vietnamese. We no longer fear them; in all our battles we are mindful of the Three Jewels; the Buddha, the law and the monastic community".^[13] After his victory at Preak Touch, Oknha Mey sent letters to other governors in Southwestern Cambodia including Oknha Thibes Sangkream Ke the governor of Kampong Saom, Oknha Sena Anchit Mau the governor of Kampot, Oknha Pisnulok Preak the governor of Treang and Oknha Chey Youtthea Ma the governor of Prey Kabbas, encouraging all of the governors to arise against the Vietnamese Trấn Tây regime.

On 7 September 1840, the Siam-backed Oknha Chet,^[8] a Cambodian official in Baray, rallied the whole Khmer population of Kampong Svay or Hải Đông district, including the towns of Kampong Svay, Baray, Cheung Prey, Kampong Siem and Steung Trang to arise against the Vietnamese regime and lynch Vietnamese people in the area. The whole Vietnamese bureacracy and also the pro-Vietnamese Cambodian clique in the area had to flee to Srey Sonthor. Oknha Chet then went to join Oknha Dechou Mich the governor of Kampong Svay, where he met delegates of the pro-Siamese Cambodian Prince Ang Duong. The uprising of Oknha Chet and Oknha Dechou Mich in Kampong Svay–Baray district was encouraged and endorsed by the Siamese of Battambang and Siemreap.^[21] Chaophraya Bodindecha even made Oknha Chet the claiming Chauvea Tolaha or Prime Minister of Cambodia, though this claim was not affirmed by any Khmer rulers. Oknha Pechdechou the governor of Cheung Prey and Oknha Montrey Sneha the governor of Kampong Siem were loyal to Vietnam so they were expelled by Oknha Chet from their towns and took refuge in Phnom Penh.

Oknha Chet and Okha Dechou Mich of Kampong Svay rallied 1,000 Khmer men^[21] in the Kampong Svay district to attack Kampong Thom or Hải Đông, the Vietnamese headquarter of the region, about fifteen kilometers to the southeast of Kampong Svay. The Tuyên phủ of Kampong Thom Trần Văn Thông and the Lãnh binh commander Hoàng Phước Lợi^[21] defended Kampong Thom against Khmer attackers. Oknha Chet and the Khmers retreated. Trần Văn Thông then sent Hoàng Phước Lợi out to pursue the Khmers. However, Oknha Chet ambushed the Vietnamese and killed Hoàng Phước Lợi.^[21] Oknha Chet then established his clique over the Kampong Svay area, with the Vietnamese restricted to Kampong Thom, supported by Siam.

Pursat or Hải Tây was a regional administrative center in Trấn Tây Cambodia, where a Vietnamese Tuyên phủ governor was appointed. Pursat held jurisdiction over the southwestern shore of Tonle Sap Lake and its governors held the title Oknha Surkealok.^[1] Pursat connected to the Siam-controlled Battambang via Moung Reussei. On 11 September 1840,^[8] Oknha Surkealok Muk (known as Sa Mộc^[21] in Vietnamese sources) took his family to walk from Pursat to Battambang, where he met the Siamese grand commander Chaophraya Bodindecha. Oknha Surkealok Muk complained to Bodindecha that the Khmers in Pursat had been suffering from Vietnamese rule and Surkealok Muk himself had been in an uneasy row with the Vietnamese Tuyên phủ of Pursat Nguyễn Song Thành. Surkealok Muk told Bodindecha that he had been rallying the local Khmers of Pursat to support the Siamese and if Bodindecha marched from Battambang to Pursat, the local Khmer would come to aid the Siamese.

Earlier in 1832, an Oknha Surkealok governor of Pursat named Kas had rebelled against the pro-Vietnamese King Ang Chan.^[1] Oknha Surkealok Kas fled to take refuge in Bangkok. Defection of Oknha Surkealok Kas to Siam in 1832 was one to the main causes of the Siamese invasion of Cambodia in 1833 and defection of Oknha Surkealok Muk the Pursat governor to the Siamese in September 1840 would also be one of the precipitating events of another Siamese invasion of Cambodia two months later in November 1840. Bodindecha brought Oknha Surkealok Kas the former governor of Pursat with him to Battambang. After the defection of Oknha Surkealok Muk to Siam, the Vietnamese appointed Oknha Vibolreach Long as the new Khmer governor of Pursat. However, Oknha Vibolreach Long soon rebelled and joined Oknha Muk on the Siamese side.^[8]

On 11 September 1840,^[20] Oknha Reachea Dechea Nong and Oknha Norea Thuppedey Mouk gathered 4,000 able-bodied Khmer men in the southern vicinity of Phnom Penh and took position at Kien Svay, just fifteen kilometers to the southeast of Phnom Penh on the Mekong, where they were joined by Oknha Thommeadecho Meas the governor of Ba Phnum. Oknha Reachea Dechea Nong then declared himself a Chakrey Minister of War and Oknha Norea Thuppedey declared himself Kralahom Minister of Navy,^[22] without any affirmation from Cambodian royalty. The self-proclaimed Oknha Chakrey Nong emerged powerful, said to take control over all area to the east of Phnom Penh. At his instigation, the Khmer people generally arose and insurrected to lynch and kill the Vietnamese immigrants in the whole Eastern Cambodia, causing an exodus of Vietnamese people to take refuge in Định Tường province^[21] in Mỹ Tho.

Next day, on September 12,^[20] Oknha Chakrey Nong sent letters to Oknha Outey Thireach Hing of Samraong Tong and Oknha Vongsa Anchit Mey of Bati, who had arisen to the west of Phnom Penh, urging them to cooperate in a joint attack on the Trấn Tây citadel. However, Oknha Hing and Oknha Mey disagreed, saying that they should not attack the citadel in wet season with high water levels and they should wait for the dry season. The Vietnamese, however, did not wait for the dry season. On 29 September 1840,^[20] Trương Minh Giảng sent Oknha Veang Tom, the pro-Vietnamese Cambodian Minister of Palace Affairs, to lead the Cambodian–Vietnamese forces of 2,500 men and 70 war vessels to attack Oknha Chakrey Nong and his clique at Kien Svay. Oknha Chakrey Nong prevailed in the Battle of Kien Svay, repelling Oknha Veang Tom back to Phnom Penh.

Two weeks later, on October 12,^[20] Trương Minh Giảng again sent 80 war vessels to attack Chakrey Nong at Kien Svay, during which Chakrey Nong prevailed for the second time, pursuing the Trấn Tây forces to Lvea Aem opposite of Phnom Penh on the eastern river bank. However, due to the lack of weapons, Chakrey Nong could not attack the Trấn Tây citadel right away. Oknha Chakrey Nong then took position at Ba Phnum, where his ally Oknha Thommeadecho Meas was the governor, while Oknha Kralahom Mouk took position at Prey Veng,^[22] all in Southeastern Cambodia.

Oknha Chakrey Nong then sent Oknha Thommeadecho Meas the governor of Ba Phnum, along with Oknha Lu Chakrey the governor of Rumdoul and the governor of Svayyap, to lead Khmer forces to attack Thông Bình (in modern Đồng Tháp province), called Kampeap Sreka Trey by the Khmers. Trương Văn Uyển^[21] the governor of Định Tường sent Cochinchinese forces of 1,500 men to successfully repel the Khmers from Định Tường. However, Oknha Chakrey Nong would sent Eastern Cambodian forces into Định Tường several more times, leading to a protracted war with Trương Văn Uyển the governor of Định Tường.

Oknha Pisnulok Preak the governor of Treang rebelled against the Vietnamese Trấn Tây government but the Vietnamese soon laid siege on Treang. The Oknha and his town nearly fell to the Vietnamese and his fellow Cambodian Oknhas fought to relief the Vietnamese siege on his town. The Khmers were able to break off the Vietnamese siege on Treang on September 21^[8] but the Vietnamese took away Oknha Preak as captive. The Khmers pursued to rescue Oknha Preak and met the retreating Vietnamese at Kampong Prang where, according to Thai chronicles, the Khmers kill half of the Vietnamese forces.

The Vietnamese imperial court kept punishment of the Cambodian princesses a secret affair until they began to inform its officials. On 2 September 1840, the Vietnamese governor of Kampot was informed by the imperial court that the three princesses had been exiled to Saigon and the Princess Ang Pen was held in Phnom Penh for investigation (it was not revealed that Ang Pen had actually been executed by that time). The Vietnamese governor of Kampot then told Oknha Sena Anchit Mau the governor of Kampot about the news, upsetting the whole Khmer officialdom in the town. On 15 September 1840,^[20] Oknha Sena Anchit Mau and the Cambodians of Kampot arose, attacking and seizing the towns of Kampong Bay and Kampong Kes in Kampot held by the Vietnamese, lynching and murdering the Vietnamese in the towns.

On 29 September 1840, Lê Quang Huyên the Vietnamese governor of Hà Tiên sent 500 Vietnamese men and 30 war vessels to attack Kampot in retaliation. The Vietnamese forces from Hà Tiên reached Kampot on October 9 as Oknha Mau defended his town. The battle was fought for three days from October 9 to October 11.^[20] The Khmers of Kampot prevailed but with great difficulty. Oknha Vongsa Anchit Mey of Bati had to send some forces to help Oknha Mau of Kampot to repel the Vietnamese.

Oknha Vongsa Anchit Mey of Bati sent a letter to his uncle Oknha Chey Youtthea Ma the governor of Prey Kabbas, urging his uncle to arise and overthrow the Vietnamese yoke. On 3 October 1840,^[20] Oknha Ma led the Khmers of Prey Kabbas to arise and lynch the Vietnamese in his town. Oknha Chey Youtthea Ma then resigned from his governorship of Prey Kabbas, allowing Oknha Chey Youtthea Ton to take over.

As the Vietnamese came from Hà Tiên, Oknha Sena Anchit Mau sent his Khmer forces of 2000 men under Oknha Youtthea Sena Tieng to attack Hà Tiên in late October 1840 in retaliation. In the same time, Lê Quang Huyên sent Hà Văn Củ^[21] to bring the Vietnamese forces from Hà Tiên to attack Kampot. The Cambodians and the Vietnamese met along the way, leading to a battle that the Khmers prevailed and Hà Văn Củ was injured. Cambodian victory allowed Oknha Youtthea Sena Tieng to continue his Khmer army to attack Hà Tiên itself. Coincidentally or not, the local Khmer Krom leaders named Kỳ La and Việt Tốt^[7] in Tĩnh Biên town, which situated between Hà Tiên and Châu Đốc, arose in October 1840, killed local Vietnamese officials and marched to attack Hà Tiên. During this Khmer attack on Hà Tiên, the Vietnamese suffered casualties as many were killed.

With critical situation in Hà Tiên for the Vietnamese, Dương Văn Phong the Tổng đốc An Hà or governor of An Giang and Hà Tiên brought forces from Châu Đốc to relief the Khmer attack on Hà Tiên. Though struggling, Dương Văn Phong and Lê Quang Huyên eventually managed to push the attacking Khmers out of Hà Tiên. Oknha Youtthea Sena from Kampot was killed during this battle at Hà Tiên. Phạm Văn Sĩ^[21] the Vietnamese commander at Kampong Saom broke through the Cambodian siege and brought his forces to successfully retake the Vietnamese Kampong Bay fort in Kampot, called Quảng Biên, prompting Oknha Sena Anchit Mau of Kampot to flee and took position elsewhere. Action of Phạm Văn Sĩ turned the tide of war in favor of the Vietnamese on the Kampot–Hà Tiên corridor. The Cambodians of Kampot were poorly-armed and untrained, having mostly blades and sticks, while the Vietnamese were trained and had muskets.

Oknha Outey Thireach Hing of Samraong Tong, Oknha Vongsa Anchit Mey of Bati, Oknha Chey Youtthea Ma the governor of Prey Kabbas, Oknha Pisnulok Preak of Treang, Oknha Sena Anchit Mau of Kampot, Oknha Thibes Sangkream Ke of Kampong Saom and the clique of the self-proclaimed Oknha Chakrey Nong including Oknha Thommadechou Meas the governor of Ba Phnum all rebelled against the Vietnamese rule in Cambodia. These towns were in the vicinity of Phnom Penh and had been under direct administration of the Trấn Tây government. These Oknhas were the first to be affected by Vietnamese government reforms to integrate them and to strip their powers. They were also the first to be informed of the news of Vietnamese treatment of Khmer royalty. When Lê Văn Đức reported the general Cambodian rebellion to Minh Mạng in September 1840,^[7] the Vietnamese Emperor Minh Mạng became furious;

Sometimes the Cambodians are loyal; at other times they betray us. We helped them when they were suffering, and lifted them from the mud... Now they are rebellious: I am so angry that my hair stands upright... Hundreds of knives should be used against them, to chop them up, to dismember them.

^[12]

The Vietnamese were also surprised by the coordination among the Oknhas governors in their military actions.^[13] In early stages, this movement lacked a single unified leader. The Vietnamese suspected Siamese instigation of this Cambodian uprising,^[13] which was partly true. Some rebelling Oknhas, most notably Oknha Chet of Baray, had apparent Siamese endorsement. However, the Siamese efforts concentrated on Pursat and Kampong Svay, not penetrating into the vicinity area of Phnom Penh and Southern Cambodia, where the Oknhas seemed to operate independently of Siamese influences until mid-November 1840 when they began to accept Siamese support and rally to Ang Duong as their candidate for Cambodian kingship.

Since 1836, Trương Minh Giảng had been concurrently holding the positions of Trấn Tây tướng quân or Govenor-General of Cambodia and Tổng đốc An Hà or governor of An Giang and Hà Tiên provinces. With the advent of Cambodian rebellion in September 1840, Minh Mạng moved Dương Văn Phong from the position of Tham tán Đại thần or deputy Governor-General to the Tổng đốc An Hà governor of An Giang and Hà Tiên, while Lê Văn Đức was made Tham tán Đại thần or deputy of Trấn Tây instead.^[7] When the Khmers attacked Hà Tiên in October 1840, Minh Mạng sent Phạm Văn Điển as Kinh lược đại thần (經略大臣) or Military Strategist of Trấn Tây.^[7]

Trương Minh Giảng and the Trấn Tây government faced manpower shortage problem as they could only rely on the Vietnamese and few loyal Khmers to fight for them so Trương Minh Giảng asked Emperor Minh Mạng to send more troops to suppress the rebellion in Cambodia.^[1] Minh Mạng commanded that 10,000 Southern Vietnamese military men from Cochinchina sent into Cambodia.^[21] The first batch arrived, composing of 1,000 men from An Giang (Châu Đốc), 1,000 men from Vĩnh Long (Long Hồ), 1,000 men from Gia Định (Saigon) and 500 men from Định Tường (Mỹ Tho) with total of 3,500 men. Second batch arrived, composing of 1,500 men from Gia Định, 2,000 men from Vĩnh Long, 1,000 men from Định Tường, 500 men from An Giang and 500 men from Biên Hòa with total of 5,500 men.^[21] However, these were barely satisfactory. Trương Minh Giảng and Dương Văn Phong had to make deals to bring other volunteers unit from Cochinchina or Southern Vietnam into Cambodia.^[21] Minh Mạng also told the Vietnamese commissioners in Cambodia not to fight every rebelling Oknhas but to focus on holding vital regional centers of Hải Đông (Kampong Thom) and Hải Tây (Pursat), which bordered Siam-controlled territories.^[21]

As Oknha Surkealok Muk the governor of Pursat had defected to the Siamese at Battambang, Trương Minh Giảng sent commander Võ Đức Trung to lead Khmer–Vietnamese from Phnom Penh to take control of Pursat.^[21] Võ Đức Trung marched along the southwestern shore of Tonle Sap Lake and fought against the rebelling Oknhas; Oknha Chet and Oknha Sena Reachea Sangkream the governor of Kampong Chhnang, near Kampong Chhnang. Võ Đức Trung prevailed over the Khmers. who fled into the jungles.^[21] Võ Đức Trung then proceeded to take control of Pursat.

Not all of the Cambodian officials rebelled against Vietnamese rule. There were some Khmer officials who still "dressed in Vietnamese costume and fought for the Vietnamese".^[20] These included Oknha Veang Tom the Minister of Palace, Oknha Srei Thommea Thireach, Oknha Reachea Sneha the governor of Sambok (brother of Samdech Chauponhea Hu), Oknha Pechdechou the governor of Cheung Prey and Oknha Montrey Sneha the governor of Kampong Siem, though the pro-Vietnamese Khmer governors had been dislodged from their cities. With the widespread of lynching frenzy on Vietnamese people in Cambodia, only Phnom Penh and Sambok still stood as the fortresses of the pro-Vietnamese clique.

The Siam-backed Oknha Chet of Baray, who had instigated the general Khmer uprising against Vietnamese rule in Kampong Svay and Baray areas, sent letters to the rebelling Cambodian governors Oknha Outey Thireach Hing of Samraong Tong, Oknha Vongsa Anchit Mey of Bati, Oknha Pisnulok Preak of Treang, Oknha Chey Youtthea Ton of Prey Kabbas, Oknha Sena Anchit Mau of Kampot and Oknha Thibes Sangkream Ke on 26 October 1840.^[20] In the letters, Oknha Chet asserted his dominance over other rebelling Oknhas as the main agent working for Siam in Cambodia, declaring that the Siamese commander Bodindecha had made him Chauvea Tolaha or Prime Minister of Cambodia. Though the Oknhas did not care about Chet, his letters made the other rebelling Oknhas aware of potential Siamese support to their cause. The Cambodian uprising suffered from inferior weaponry and supply, becoming exhausted and they would soon realize they needed Siamese aid against the Vietnamese.

With the arrival of dry season in early November 1840, the rebelling Oknhas moved their forces to encamp at the outskirts of Phnom Penh to enclose on the Trấn Tây citadel;^[20]

• Oknha Outey Thireach Hing of Samraong Tong sent Oknha Sena Reachea Sangkream of Kampong Chhnang to bring 2,600 Khmer men to station in the outskirts of Phnom Penh.
• Oknha Vongsa Anchit Mey of Bati sent Oknha Akkareach Prom to bring 2,200 Khmer men to station in the outskirts of Phnom Penh.
• Oknha Chey Youtthea Ton the incumbent governor of Prey Kabbas sent Oknha Chey Youtthea Ma the resigned governor of Prey Kabbas to bring 950 Khmer to encamp in the outskirts of Phnom Penh

During this Khmer enclosing on the Trấn Tây citadel in Phnom Penh, Chaophraya Bodindecha sent Phraya Ratchanikun to bring Lao and Northern Khmer forces of 13,000 men to Kampong Svay on 3 November 1840^[8] to attack the Vietnamese at Kampong Thom and Chikraeng on the northern shores of Tonle Sap lake, with the aid from Oknha Dechou the Cambodian governor of Kampong Svay. Phraya Ratchanikun and Oknha Dechou seized the town of Chikraeng from the Vietnamese. On November 10, Chaophraya Bodindecha and Phra Narinyotha Nong the vice-governor of Battambang sent letters to the Oknhas of Southern Cambodia, urging them to attack the Vietnamese. On November 16, Bodindecha sent Phra Phirenthorathep Kham, son of Chaophraya Nakhon Ratchasima Thong-in the governor of Nakhon Ratchasima (Bodindecha's brother-in-law), to lead 2,788 Lao men to attack the Vietnamese-held Pursat.^[8]

After receiving the letters from the Siamese, the Southern Cambodian Oknhas allied themselves with Siam, sending separate flattering letters on 17 November 1840^[20] to Bodindecha;

• Oknha Outey Thireach Hing of Samraong sent a letter to Bodindecha, professing himself to be a Siamese subject, lamenting that the Cambodian uprising movement lacked a single unified leader and wished that the Prince Ang Duong could be one.
• Oknha Sena Anchit Mau of Kampot sent a letter to Bodindecha, complaining that he had been struggling to resist Vietnamese attacks from Hà Tiên due to his lack of weapons and supplies, asking for Ang Duong to bring forces to aid Kampot.
• Oknha Vongsa Anchit Mey of Bati, Oknha Chey Youtthea Ton of Prey Kabbas and Oknha Thibes Sangkream Ke of Kampong Saom wrote a joint letter to Bodindecha, asking Bodindecha to release Ang Duong to be the leader of Khmer resistance against Vietnamese rule and expressing their wishes that Cambodia would be like during the reign of Ang Eng and the regency of Chauvea Tolaha Pok in the 1790s, when Siam dominated Cambodia.

Among the Southern Cambodian Oknhas, only the self-proclaimed Oknha Chakrey Nong and his vast clique in Southeastern Cambodia remained independent, not submitting to the Siamese. Confident of local Khmer support to his cause, Bodindecha sent his son Phra Phromborrirak and his brother-in-law Chaophraya Nakhon Ratchasima to bring Lao Siamese forces of 2,445 men to attack Pursat on November 20. Next day, on 21 November 1840, Bodindecha himself marched the main Siamese forces of 3,520 men to attack Pursat. The Khmer Oknhas chose Oknha Surkealok Muk and Oknha Vibolreach Long as their representatives to formally deliver eighteen letters, requesting the Siamese to release Prince Ang Duong to be the leader of this anti-Vietnamese movement,^[8] to Bodindecha at Pursat.

In 1840, the Cambodian queen Ang Mey was deposed by Vietnamese; she was arrested and deported to Vietnam along with her relatives and the royal regalia. Spurred by the incident, many Cambodian courtiers and their followers revolted against the Vietnamese rule.^[23] The rebels appealed to Siam who supported another claimant to the Cambodian throne, Prince Ang Duong. Rama III responded and sent Ang Duong back from exile in Bangkok with Siamese troops to install him on the throne.^[24]

The Vietnamese were attacked from both Siamese troops and Cambodian rebels. In Cochinchina, several rebellions broke out. The main strength of the Vietnamese marched to Cochinchina to put down those rebellions. Thiệu Trị, the new crowned Vietnamese emperor, decided to a peaceful resolution.^[25] Trương Minh Giảng, the Governor-General of Trấn Tây (Cambodia), was called back. Giảng was arrested and later committed suicide in prison.^[26]

Ang Duong agreed to place Cambodia under joint Siamese-Vietnamese protection in 1846. The Vietnamese released Cambodian royalties and returned the royal regalia. In the same time, Vietnamese troops withdrew out of Cambodia. Giving Cambodians independence. Though there were still a few Siamese troops stayed in Cambodia, the Cambodian king had greater autonomy than before.^[27]

Footnote

Citations

• Chandler, David P. (2008). A history of Cambodia (4th ed.). Westview Press. ISBN 978-0813343631.
• Harris, Ian (2005). Cambodian Buddhism, History and Practice (PDF). University of Hawaii Press. ISBN 0-8248-2765-1. Archived from the original (PDF) on March 16, 2015.

• Cambodian rebellion (1811–12)
• Cambodian rebellion (1820)
• Vietnamese invasions of Cambodia
• Siamese–Vietnamese War (1841–1845)
• Hà Tiên Rebellion (1840)
• Ba Xuyên Rebellion (1841)
• Thất Sơn Rebellion (1841)
• Lâm Sâm Rebellion