My Lai Massacre, Vietnam, 1971 Photo WIkileaks Commons / Library of Congress
Vietnam was called "The Livingroom War".
That's because it was the first war in US history that came along with live television coverage.
For the first time, Americans could watch the progress or the war, daily, from their homes. Most of it largely uncensored.
What they saw shocked them.
Up until Vietnam, warfare had been carried out in private. It was always bloody, always ugly,