Frazier was the underdog. The youngest of 12 born into poverty in rural South Carolina, he arrived in Philadelphia as a married 16-year-old, and was working at a slaughterhouse when he took up boxing. As an amateur, he won three Golden Gloves titles and, in 1964, an Olympic gold medal. Over the next five years, Smokin' Joe knocked out 23 of 26 opponents en route to becoming the undisputed heavyweight champion in 1970.
Ali was the favorite. Born Cassius Clay in Louisville, Ky., he won Olympic gold in 1960 and the heavyweight championship of the world four years later, at 22. The day after he won the title, he announced his conversion to Islam and assumed the name Muhammad Ali. By 1967, he had posted a 31-0 record, knocking out 25 of his opponents. But he was stripped of his title after he claimed his religion forbade him from participating in the Vietnam War.
It was not a popular stand. Vietnam had already claimed the lives of 30,000 young Americans, and the nation was divided over it. It was also a time of activism and militancy among African Americans, especially after the assassination of Martin Luther King Jr. Vilified as a draft dodger by politicians and boxing officials, Ali was sentenced to five years in prison for draft evasion, though the Supreme Court later overturned his conviction.
Barred from fighting for nearly four years of his prime, Ali supported himself by speaking on college campuses about race, religion, and the war. He became a symbol of the antiestablishment. Meanwhile, Frazier, the hardworking, law-abiding, churchgoing family man, became a hero of pro-war conservatives.
When Ali returned to the ring in 1970, he sought to reclaim the heavyweight title. He also demeaned Frazier, taunting him as an "Uncle Tom." The following year, the two pugilists met in a 15-round championship bout billed as the "Fight of the Century."
Although Ali dominated the first three rounds, he was visibly tired after the sixth. Frazier finally decked him with a sledgehammer left hook early in the 15th round. Ali, the right side of his jaw swollen grotesquely, got up from the canvass quickly and managed to complete the round. But a few minutes later, the judges awarded Frazier a unanimous decision, dealing Ali his first professional loss.
Frazier and Ali would fight each other twice more, and Ali would win both matches. But Smokin' Joe had secured his place in history, defending his title against a fighter widely considered the greatest of all time. The 1976 movie Rocky famously featured some of Frazier's training techniques, including punching cow carcasses and running the Art Museum steps.
Frazier retired in 1981 with a career record of 32 wins, four losses, and one draw, with 27 knockouts. Although he traded jibes with Ali for the next three decades, he suggested their rivalry had finally subsided in a 2009 Sports Illustrated interview, saying, "Nobody has anything but good things to say about Muhammad now."
Ali made his peace, too. "The world has lost a great champion," he said after Frazier's death. "I will always respect and admire him."
William C. Kashatus is a historian and writer. He can be contacted at firstname.lastname@example.org.