Parole's sire was the great Leamington who also produced Longfellow, Aristides (named by his breeder for Aristides Welch who had imported Leamington into the US), winner of the first Kentucky Derby, and Iroquois, first American bred horse to win the Epsom Derby and the St. Leger Stakes.
According to the National Museum of Racing and Hall of Fame, at two Parole was considered the best juvenile racing. He was also, by many, thought the best four- and five-year-old. At four he beat the good gelding Shirley (by Lexington) in the August Stakes. Shirley had won the Preakness Stakes. Parole also won the Saratoga Cup, but more importantly he beat both Ten Broeck and Tom Ochiltree in the Baltimore Special at Pimlico Race Course on October 24, 1877. Both of these horses were considered the best horses in the West as well as the East. In 1877, Ten Broeck had won eight races in a row. One was a walkover since no one would enter against him, and two were races against time for the same reason. Tom Ochiltree, owned by Pierre Lorillard’s brother George, was huge, standing above sixteen hands. One of the last sons of Lexington, he, like Shirley, had won the Preakness Stakes. Parole was younger than either of them. Earlier he’d beaten Tom Ochiltree in the Saratoga Cup, but in later races, Tom had beaten him twice. Congress adjourned for the day to attend this Baltimore, Maryland event. Throughout most of the race, Ten Broeck led and Parole trailed. But by the end Parole was coming on fast. He lapped Tom Ochiltree and then passed Ten Broeck, taking the race by four lengths.
Parole was the only horse to ever defeat Ten Broeck.
The owners of both losers reported that their horses had been seen coughing before the race. In any case, both horses were retired at the end of the year. But Parole, as a gelding, went on racing.
Although Parole was owned by the Pennsylvanian breeder Aristides Welch, Lorillard took his brother George Lorillard’s horse, Duke of Magenta (by Lexington), and his stablemate, the six-year-old Parole, as well as a number of other horses (Cherokee, Friar, Pappoose, Geraldine, Boreas, Nereid, and Uncas), to England in a serious effort to have an American horse win an English race. Parole went as a trial horse.
On his arrival in England, the English press called Parole the “Yankee Mule.” Sam Hildreth, in his book "The Spell of the Turf," said he was called "light-necked, rough-coated, leggy and curby knocked."
While there, the Duke of Magenta became ill with influenza, allowing Parole an opportunity to prove his worth. Within one week in April, Parole won the Newmarket Stakes (defeating Isonomy) and the City and Suburban Handicap (defeating 17 horses, including Ridotto). The following day he won the Great Metropolitan which was set at two and a half miles. Only one other horse started with him, Castlereagh, because no other owner wanted to continue competing against Parole. Parole carried 124 pounds against Castlereagh's 110. The English were amazed at this performance but American horses were used to running in grueling heats.
Parole took four back-to-back races as soon he arrived home, and he went on racing until 1884 when he was eleven years old, winning 59 of his 127 starts and earning over $80,000.
When he was finished racing, Parole was America's leading money winner and the best gelding of his era.
Parole was inducted into the Hall of Fame in 1984.