Cambodian campaign participant South Vietnam
The Cambodian campaign (also known as the Cambodian incursion and the Cambodian liberation) was a brief series of military operations conducted in eastern Cambodia in 1970 by South Vietnam and the United States as an extension of the Vietnam War and the Cambodian Civil War. Thirteen major operations were conducted by the Army of the Republic of Vietnam (ARVN) between 29 April and 22 July and by U.S. forces between 1 May and 30 June 1970.
The objective of the campaign was the defeat of the approximately 40,000 troops of the People's Army of Vietnam (PAVN) and the Viet Cong (VC) in the eastern border regions of Cambodia. Cambodian neutrality and military weakness made its territory a safe zone where PAVN/VC forces could establish bases for operations over the border. With the US shifting toward a policy of Vietnamization and withdrawal, it sought to shore up the South Vietnamese government by eliminating the cross-border threat.
A change in the Cambodian government allowed an opportunity to destroy the bases in 1970, when Prince Norodom Sihanouk was deposed and replaced by pro-U.S. General Lon Nol. A series of South Vietnamese–Khmer Republic operations captured several towns, but the PAVN/VC military and political leadership narrowly escaped the cordon. The operation was partly a response to a PAVN offensive on 29 March against the Cambodian Army that captured large parts of eastern Cambodia in the wake of these operations. Allied military operations failed to eliminate many PAVN/VC troops or to capture their elusive headquarters, known as the Central Office for South Vietnam (COSVN) as they had left a month prior, but the haul of captured material in Cambodia prompted claims of success.