Today in history on April 28, 1967, in the midst of the Vietnam War, world-renowned heavyweight champion Muhammad Ali refused induction into the U.S. military.

Ali, then Cassius Clay, began his boxing career when he was just twelve years old. He jumped in the ring, quickly building up his strength, speed, and agility. And he was determined to be the best.

By the time he graduated high school, Clay had won multiple amateur titles and had secured numerous victories. Following high school, he competed in the 1960 Summer Olympics where he won the light heavyweight gold medal.

In 1964, Clay went up against reigning heavyweight champion Sonny Liston. Confident as he was, Clay was fully expecting a victory. Prior to the fight he teased Liston that he was going to “float like a butterfly, sting like a bee.” Clay predicted correctly and following the match, he shouted, “I am the greatest!” At just twenty-two years, old he walked away as the newly crowned heavyweight champion of the world.

Shortly after his big win, Clay converted to Islam and changed his name to Muhammad Ali. Ali continued his streak, keeping a tight grip on his coveted title.

However, his elation would soon be ripped away. On April 28, 1967, Ali refused induction into the U.S. armed forces, a direct violation of the law. Ali said he didn’t have any quarrel with the Vietnamese, and asked, “Why should they ask me to put on a uniform and go ten thousand miles from home and drop bombs and bullets on brown people in Vietnam while so-called [black] people in Louisville are treated like dogs and denied simple human rights?”

Ali was arrested, charged, and convicted of draft evasion. He was sentenced to prison, charged a hefty $10,000 fine, stripped of his title, and banned from boxing for three years. Fortunately for Ali, he was able to avoid prison-time as he appealed his conviction, declaring that the war went against the teachings of the Qur’an. Ali vocally stated his opposition to America’s involvement in the war.

Ali was finally able to return to boxing in 1970. It was not for another year, however, until his case would make it to the United States Supreme Court. On June 28, 1971, the Supreme Court voted unanimously to overturn Ali’s conviction.

Ali continued with his career, jumping right back into the swing of things. He went on to become the heavyweight champion of the world for the second time in 1974 when he defeated 25-year champion George Foreman. Then, in 1975, he went up against his longtime rival Joe Frazier. Ali defeated Frazier and maintained his championship title.

With 56 wins, just 5 losses, and 37 knockouts, he retired at 39-years-old. Ali accomplished so much throughout his life, both within and outside of his boxing career. The famous three-time heavyweight champion of the world, Muhammad Ali, is still a beloved icon and role model for so many.