In late 1964, when I'd been with CBS News a little more than four months, I went to Vietnam for the first time. There were 23,000 American troops there, acting as advisers to the South Vietnamese.
In two more assignments over the next eight years, I saw American troops go from being advisers to doing most of the fighting.
The troop commitment grew to half a million. The military measured progress in body counts, but no matter how many bodies they counted, the North Vietnamese and the Viet Cong stayed on the offensive.
Fifty-eight thousand Americans died, as did an estimated 5 million Vietnamese.
As the American public tired of the sacrifice of lives and treasure, U.S. troop numbers in Vietnam declined to almost nothing.
Then, 40 years ago this month, I went back for the fourth time. The North Vietnamese were advancing on Saigon, the capital city of the South. The U.S. was out of Vietnam, but the thousands of South Vietnamese whose lives were touched by the U.S. presence were not.
They lined up in front of the U.S. Embassy, desperate to get out before the communists came - as everyone knew they would. It was a time of turmoil and despair.
Some of luckier ones made it onto U.S. Air Force evacuation flights out of Saigon.
Others stormed the walls of the embassy on April 30, hoping to get on a helicopter to the safety of a U.S. Navy ship offshore.
I had left 36 hours before and was able to report on the collapse from Hong Kong.
We left behind many who still suffer - veterans, children with birth defects likely caused by chemicals used in the war, children who still lose limbs to the bombs and mines left behind.
And here at home, 40 years later, the war is a distant memory for most Americans. But not for those whose lives were upended - the wounded, the traumatized, the bereaved.
If there's any comfort to be had for the suffering, it's in the considerable efforts both here and in Vietnam at healing the wounds. Those who were touched by the war will never forget it. But I hope they find some measure of peace.