How did US involvement in the Vietnam war end?

The TET offensive of 1968, was the "hand writing on the wall", with a little assistance from TV anchorman, Walter Cronkite. In 1969, President Nixon put forth the "Nixon Doctrine" that spelled out his plan for Vietnamization and the subsequent withdrawal of US troops from Vietnam. By the end of his first term, Nixon had withdrawn some 90% of the troops after assuring the public that the US would achieve "peace with honor."