Muhammad Ali, for years to come, was the best known American individual opposed to the Vietnam war. Far more than more political figures - he had the greater recognition. When Ali returned to America in early 1967 he faced
a daunting choice - give in, sign up with the army and cut a deal with them, or, go to jail, loose his Heavyweight crown and never fight again. But his conscience would not let him back down.
Ali was stripped of his title, charged, convicted, sentenced to five years in prison, released on bail. His passport was taken away from him and for three and a half years he was not allowed to leave the United States and not allowed to fight at all.
credit to :
http://www.newsfinder.org/site/more/muhammad_ali/