1 MAY 1970 - CAMBODIAN INCURSION - #VietnamWar
On 1 May 1970 a combined U.S. and Army of the Republic of (South) Vietnam (ARVN) force initiated Operation TOAN THANG 43 in the "Fishhook" area of Cambodia adjacent to South Vietnam's Tay Ninh Province, some 65 miles northwest of Saigon.
Officially called the "Sanctuary Offensive," the operation lasted from 1 May to 30 June 1970. The incursion into Cambodia, codenamed Operation ROCK CRUSHER by U.S. forces, included the U.S. 11th and the ARVN 1st Armored Cavalry Regiments, the 3d Brigade of the U.S. 1st Cavalry Division (Airmobile) and the ARVN 3d Airborne Brigade, plus one armor and one mechanized infantry battalion from the U.S. 25th Infantry Division and the 3d Brigade of the U.S. 9th Infantry Division, respectively - under the operational control of the 3d Brigade of the 1st Cavalry Division.
The Allied units entered Cambodia from three directions aimed at attacking the Central Office for South Vietnam (COSVN), the enemy command headquarters for operations in the southern Republic of Vietnam (RVN), or South Vietnam, and control center for enemy operations against the III Corps Tactical Zone (CTZ).
As American withdrawal from South Vietnam proceeded, increasing concern arose over the enemy's strength in the sanctuaries inside nominally neutral Cambodia. With the emergence of an anti-Communist government under Lon Nol, U.S. President Richard Nixon relaxed the restrictions on moving against enemy bases inside Cambodia. When North Vietnamese and Viet Cong forces advanced on the Cambodian capital of Phnom Penh. Lon Nol appealed for help. American and allied South Vietnamese forces began large-scale offensives in Cambodia on 1 May.