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Marciano retired in 1955, concluding an undefeated professional boxing career that spanned over eight years and 49 fights. Known as the "Rock of Brockton", Marciano held the world heavyweight title from 1952 until his retirement, successfully defending it six times. He is widely regarded as one of the greatest boxers of all time, with a knockout percentage of 87.76% and a perfect 49-0 record.