Throughout his career, Jack Dempsey achieved numerous remarkable feats that solidified his legacy in the boxing world. One of his most notable achievements was winning the world heavyweight championship in 1919 by defeating the reigning champion, Jess Willard, in a brutal match that lasted less than four rounds. Dempsey successfully defended his title multiple times, engaging in epic battles with formidable opponents such as Georges Carpentier and Luis Firpo, further cementing his reputation as a dominant force in the ring.