Siamese–Vietnamese War (1841–1845)

Siamese–Vietnamese War (1841–1845)
	Part of Siamese–Vietnamese Wars and Vietnamese invasions of Cambodia
	; A map showing the movement of Vietnamese troops (from June to December 1845) during the Siamese-Vietnam War (1841–1845).
Date	1841–1845
Location	Cambodia, Southern Vietnam
Result	Cambodia came under joint Siamese-Vietnamese suzerainty.; Semi-independent Cambodia (Tây Thành province) became a buffer state between Siam and Vietnam.;
Belligerents
Nguyễn dynasty ; Pro-Nguyen Khmer forces	Rattanakosin Kingdom (Siam); Anti-Nguyen Khmer forces
Commanders and leaders
Emperor Thiệu Trị ; Trương Minh Giảng ; Lê Văn Đức; Phạm Văn Điển; Nguyễn Công Nhân; Nguyễn Công Trứ; Võ Văn Giải; Nguyễn Tri Phương ; Nguyễn Tiến Lâm; Nguyễn Văn Hoàng; Doãn Uẩn; Tôn Thất Nghị; Former Cambodian queen, princes and ministers:; Ang Mey; Ang Em; Chaofa Talaha (Lung)	King Rama III ; Chao Phraya Bodindecha (Sing Sinhaseni); Kromma Khun Isaret-rangsant; Chao Phraya Nakhon Ratchasima Thong-in; Chao Phraya Yommaraj Bunnak; Phra Promborrirak; Chameun Waiworanat (Chuang Bunnag); Ang Duong
Units involved
Imperial Vietnamese Army	Siamese Royal Army
Strength
At the start of the war: 5,000 Vietnamese soldiers ; 1,600 Cham–Malay soldiers ; Total (1841): 6,600 ; ; 1845 Vietnamese Dry season offensive: 20,000	35,000 Thai soldiers
Casualties and losses
Unknown	Unknown

The Siamese–Vietnamese War of 1841–1845 (Thai: อานามสยามยุทธ (พ.ศ. 2384 – พ.ศ. 2388), Vietnamese: Chiến tranh Việt–Xiêm (1841–1845), Khmer: សង្គ្រាមសៀម-យួន (១៨៤១-១៨៤៥)) was a military conflict between the Đại Nam, ruled by Emperor Thiệu Trị, and the Kingdom of Siam, under the rule of Chakri King Nangklao. The rivalry between Vietnam and Siam over the control of the Cambodian heartlands in the Lower Mekong basin had intensified after Siam had attempted to conquer Cambodia during the previous Siamese–Vietnamese War (1831–1834). Vietnamese Emperor Minh Mạng installed Princess Ang Mey to rule Cambodia as a puppet queen regnant of his choice in 1834 and declared full suzerainty over Cambodia, which he demoted to Vietnam's 32nd province, the Western Commandery (Tây Thành Province). In 1841, Siam seized the opportunity of discontent to aid the Khmer revolt against Vietnamese rule. King Rama III sent an army to enforce Prince Ang Duong's installation as King of Cambodia. After four years of attrition warfare, both parties agreed to compromise and placed Cambodia under joint rule.