He became an instant celebrity, hero, and record star. Then he had the fall from fame which so often accompanies meteoric rises. The Wikipedia entry tells the story. I first remember him when he was on the Ed Sullivan Show. He sang, what else, "the Ballad of the Green Berets". My father commented that there were marks on the stage telling him where to move after every verse.
The record was a tremendous hit, number one on all the charts, and, for a while, Americans prided themselves on living in a country where Green Berets died for us and were featured in John Wayne movies.
Then that summer, the song off the record charts but not out of our hearts, I heard that Staff Seargent Barry Sadler was singing (for free, no less) at the Bergen Mall. There I sat and watched the show. He was asked to sing "A Team" the follow up record, but he declined, saying he didn't remember how it went.
The next day I was back at the YMCA learning how to swim. I told my new swim-mates about seeing Barry Sadler. They were very impressed. The summer of 1966 was noteworthy for seeing Staff Seargent Barry Sadler sing and Peter Chu to swim at the YMCA.