In 1915, he decided to make an attempt to break Jones' mile record, and he trained with coach Eddie O'Connor for six months to do so. By June, he was in top form. He defeated Kiviat on June 26 in 4:15 in the Eastern Trials for the
AAU, then won a mile at the Milrose AA in 4:17 a few weeks later. He chose July 16 to make a special attempt to break the mile record. But he was not just aiming for Jones' world record – he was also aiming for Walter George's professional record of 4:12, set in 1886. The
Harvard track at
Allston, Massachusetts was extremely fast and the weather was perfect for the attempt. Five seasoned timers were on hand, as were three pace-setters who were given handicaps to best assist Taber in his quest. J.W. Ryan, who was given a 10-yard lead, set a fast pace, clocking 58 s for the first lap. Then, D.S. Mahoney, who had been given a 120-yard lead, took up the pace-setting duties and pulled Taber through the half in 2:05, then 3:13 at the three-quarter mark. J.M. Burke, given a lead of 355 yards, carried Taber on through the final lap, and the crowd, sensing a record, cheered loudly: Taber passed 1500 m unofficially in 3:55, faster than the world record, and it was clear Jones' amateur record would fall. Taber passed Burke into the homestretch and slowed, but kept his form and crossed the finish line. After a few moments, the official time was announced as 4:12, and pandemonium ensued, with the crowd invading the track. Taber had beaten George's 29-year-old professional record by of a second, and had become the fastest miler in history. While some raised objections over the pacing involved and the lack of any race, the IAAF ratified the record, and it stood until
Paavo Nurmi eclipsed it in 1923. ==Personal life==