Iroquois was not particularly tall for a Thoroughbred, maturing at . Though he matured slowly, he won four of his two-year-old races that he ran on British soil. In his first race as a three-year-old, Iroquois placed in the
2,000 Guineas. Most horseman (including
Sam Hildreth) said he wasn't quite himself at the time. Even so, England's champion jockey,
Fred Archer (called "The Tin Man"), was there that day and asked for the mount in the Epsom Derby even though he was contracted to ride the horses of
Lord Falmouth. Lord Falmouth allowed Archer to ride the American horse. Iroquois and Archer (in the cherry and black colors of Lorillard) beat the favorite, Peregrine, by a neck on June 1, 1881. (Peregrine had won the 2,000 Guineas.) Archer retained the mount on Iroquois for the St. Leger on September 14, 1881. They won against a field of fourteen. Iroquois' victory made him a byword in the United States; there was an immediate upswing in American
racetrack attendance. Iroquois raced seven times as a three-year-old, winning five. As a winner of the Derby and the St. Leger, if Iroquois had won the 2,000 Guineas instead of coming in second, he would have taken England's
Triple Crown. When Iroquois was four he became a "
bleeder," meaning that he bled from his nose when making the kind of effort a
racehorse must make to be a successful contender. He also became difficult to train, probably because of this. Therefore, he did not run at four. Lorillard sent him back to the United States in July 1883. Home again, Iroquois won the
Stockbridge Cup, placed in the
Hardwicke Stakes and came in third in the
Monmouth Stakes. ==Stud record==