The provided text is an extensive biographical and career summary focusing on the legendary American professional boxer Rocco Francis Marchegiano, globally recognized as Rocky Marciano. This comprehensive profile emphasizes his unique status as the only World Heavyweight Champion to retire with an undefeated record of 49 wins and 0 losses between 1947 and 1955. The source traces his life from his early years in Brockton, Massachusetts, and military service during World War II through his notable title defenses against opponents like Jersey Joe Walcott and Ezzard Charles. His distinctive and aggressive fighting style, which included his famous "Susie Q" punch, is explored in detail, along with his meticulous training routine. Finally, the text chronicles his life after retirement, ...