Muhammad Ali was at the top of the boxing world when he made a decision that changed his life forever. On April 28, 1967, the reigning heavyweight champion refused to be inducted into the U.S. Army during the Vietnam War, saying his religious beliefs did not allow him to serve. Within hours, boxing authorities stripped him of his world heavyweight title and suspended his boxing licence, a move that kept him away from the sport during what many consider the prime years of his career.

According to History.com, Ali's refusal was based on his faith after converting to Islam. The decision quickly became one of the most debated moments in sports history, with supporters praising his principles while critics accused him of avoiding military service.

Born Cassius Marcellus Clay Jr. in Louisville, Kentucky, on January 14, 1942, Ali first rose to global fame after winning a gold medal at the 1960 Rome Olympics. He turned professional later that year and built an unbeaten record before defeating Sonny Liston on February 25, 1964, to become heavyweight champion.

Soon after the victory, he announced his conversion to Islam and adopted the name Muhammad Ali. Nation of Islam leader Elijah Muhammad said, "This Clay name has no meaning. Muhammad Ali is what I will give him as long as he believes in Allah and follows me."

As the Vietnam War continued, Ali's application for conscientious objector status was rejected. On April 28, 1967, he appeared at an induction centre in Houston, Texas. According to The Guardian, Ali stood with other men being called for military service but refused to step forward when his name was called. He was warned about the consequences, given another chance, and refused again before signing a statement confirming his decision.

Ali had already made his position clear. He famously said, "I ain’t got no quarrel with those Vietcong."

He also explained his stand in a written statement, saying, "It is in the light of my consciousness as a Muslim minister and my own personal convictions that I take my stand in rejecting the call to be inducted. I do so with the full realisation of its implications. I have searched my conscience."

Ali further defended his championship, stating, "I had the world heavyweight title not because it was given to me, not because of my race or religion, but because I won it in the ring. Those who want to take it and start a series of auction-type bouts not only do me a disservice, but actually disgrace themselves... Sports fans and fair-minded people throughout America would never accept such a title-holder."

Soon after leaving the induction centre, the New York Boxing Commission, the World Boxing Association and the Texas Boxing Commission withdrew recognition of Ali as heavyweight champion and suspended his licence.

On June 20, 1967, he was convicted of draft evasion. According to History.com, he received a five-year prison sentence, a $10,000 fine and a three-year ban from boxing. However, he remained free while appealing the verdict and never spent time behind bars.

Ali also formally declared, "I refuse to be inducted into the Armed Forces of the United States because I claim to be exempt as a minister of the religion of Islam."

Ali returned to boxing in October 1970 with a victory over Jerry Quarry. Although he suffered the first loss of his professional career against Joe Frazier in the famous "Fight of the Century" in 1971, he continued rebuilding his career.

On June 28, 1971, the U.S. Supreme Court unanimously overturned his conviction, clearing him of draft evasion charges. In the years that followed, Ali defeated Joe Frazier in their rematch, reclaimed the heavyweight championship by beating George Foreman in the iconic "Rumble in the Jungle" in 1974 and later defeated Frazier again in the legendary "Thrilla in Manila."

Ali retired with a professional record of 56 wins and five losses. He became the first boxer to win the world heavyweight title three times. Long after his boxing career ended, his decision in 1967 remained one of the defining moments of his legacy, remembered as an example of an athlete willing to risk everything for his beliefs.