Gladiateur's owner sent him to England to be trained by Tom Jennings, Sr. at Newmarket Racecourse. Developing the colt slowly, he did not begin racing until the fall of 1864 and won only one of the three races he entered. At age three, things were very different as Gladiateur was the most dominant horse in European racing while becoming the first foreign horse to win the English Triple Crown. After winning the 1865 2,000 Guineas then the most prestigious race in England, The Derby, Gladiateur was sent to race in Paris. In front of happy fans who dubbed him "The Avenger of Waterloo", he easily won the Grand Prix de Paris.