U.S. Marines Land in Vietnam
On March 8, 1965, in an escalation of the Vietnam War, 3,500 U.S. Marines landed at Da Nang, South Vietnam. This marked the first deployment of American combat troops to Vietnam, signifying a new phase in U.S. involvement. The landing came in the wake of sustained Viet Cong attacks on U.S. and South Vietnamese targets, and represented the beginning of major ground operations by the U.S. in its attempt to counter the growing influence of Communist forces in the region.
The New York Times

Fall of Saigon
The Fall of Saigon occurred on April 30, 1975, marked by the capture of Saigon (now Ho Chi Minh City) by the People's Army of Vietnam and the Viet Cong. This event effectively ended the Vietnam War. As North Vietnamese forces advanced, the U.S. carried out Operation Frequent Wind, the largest helicopter evacuation in history, to rescue thousands of American and Vietnamese civilians. The fall marked the beginning of the reunification of Vietnam under communist control, signaling the end of South Vietnam as a state.
BBC

I've looked at life from both sides now
From win and lose and still somehow
It's life's illusions, I recall
I really don't know life at all
Joni Mitchell, Both Sides Now

Imagine, John Lennon

Viet Nam Song ‐ Live Woodstock 1969, Country Joe & the Fish

Both Sides Now, Joni Mitchell

The Ballad Of The Green Berets 1966, SSG Barry Sadler

God Bless The U.S.A., Lee Greenwood