Video: 'Vietnam: A Television History - Cambodia and Laos [8/11]' (U.S. troops leave Cambodia at 26:30)

(Tuesday, June 30, 1970; during the Cambodian Campaign, part of the Vietnam War, Cambodian Civil War, Indochina Wars and the Cold War) — The last American advisers and support troops withdrew from Cambodia today, 63 days after major allied operations began against North Vietnamese and Vietcong sanctuaries.

United States military spokesmen reported that the Saigon command headquarters had received a telephone message tonight saying that the advisers assigned to South Vietnamese units and numbering no more than two dozen as of yesterday had been withdrawn.

About 34,000 South Vietnamese troops remain in Cambodia, mostly in an area east of Phnom Penh between the capital and the South Vietnamese border.

As the last American troops pulled out, official American sources in Saigon said they had received what one of them called “crystal clear,” restrictions on what the American forces could do in Cambodia.

Video: 'Vietnam: The Ten Thousand Day War - The Village War [10/13]' (Cambodia Campaign at 33:17)

Several thousand U.S. soldiers moved across the border from South Vietnam to Cambodia’s Kampong Cham Province on May 1, 1970, expanding the American involvement in the Vietnam War to attack North Vietnamese Army (NVA) enclaves in an area known as the Fishhook.

Helicopters and ground troops of the U.S. Army’s 1st Air Cavalry Division and an airborne brigade of South Vietnam’s Army of the Republic of Vietnam (ARVN) caught the NVA off guard, while troops of the 25th Infantry Division drove their attack northward and westward; by May 3, the United States would claim 467 of the enemy had been killed, and only eight American soldiers.

Protests against the expansion of the Vietnam War began almost immediately on American college campuses.

On May 4, 1970, the unrest escalated to violence when Ohio National Guardsmen shot and killed four unarmed students (two of whom were not protesters) during the Kent State shootings.

Video: 'The Sensational 70s - 1970' (Cambodia Campaign at 16:54)

On May 15, 1970, city and state police killed two and wounded twelve at Jackson State College in Jackson, Mississippi.

Earlier, on May 8, 1970, 100,000 protesters had gathered in Washington and another 150,000 in San Francisco on only ten days notice.

Nationwide, 30 ROTC buildings went up in flames or were bombed while 26 schools witnessed violent clashes between students and police. National Guard units were mobilized on 21 campuses in 16 states.

The student strike spread nationwide, involving more than four million students and 450 universities, colleges and high schools in mostly peaceful protests and walkouts.

In all, 338 U.S. servicemen were killed (another 13 missing) in Cambodia during the unpopular 61-day incursion from South Vietnam.

Allied military operations failed to eliminate many North Vietnamese/Viet Cong 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.