The Olympic Games first introduced the modern decathlon in 1912 at the Stockholm Olympics.
The event tested athletes across ten track-and-field disciplines: 100 metres, long jump, shot put, high jump, 400 metres, 110-metre hurdles, discus, pole vault, javelin, and 1,500 metres. At Stockholm, the competition ran from July 13 to 15 and attracted 29 athletes from 12 nations.
American Jim Thorpe dominated the inaugural Olympic decathlon. He was originally stripped of his title in 1913 after officials discovered that he had previously received payment for playing baseball, violating the amateur rules of that era. Hugo Wieslander was subsequently listed as champion for decades. In 1982, the IOC restored Thorpe's status as a gold-medal winner, and in 2022 he was formally recognized as the sole Olympic champion of the 1912 decathlon.
The year 1904 can be misleading because St. Louis hosted an “all-around” competition, an earlier ten-event event with a different structure. It was not the modern decathlon. The current decathlon format was developed around 1911 and made its Olympic debut in 1912.