Samuel Doyle Riddle, the son of Samuel Riddle and Lydia Carter Doyle Riddle, was born on July 1, 1861 at Glen Riddle, Pennsylvania, a community named for his family's ancestral home in Scotland. His father, who had emigrated virtually penniless from Belfast, Ireland, eventually founded a large textile-manufacturing company near Philadelphia.
Riddle attended John Ferris Classical Academy and graduated from the Pennsylvania Military College (later Widener College) in 1879.
At the age of twenty-one he entered the family business, of which he later became president.
Growing up in the fox hunting country of eastern Pennsylvania, Riddle early became an ardent sportsman. He was an excellent judge of foxhounds, a crack shot, and an expert raccoon hunter. For many years he was president of the Rose Tree Hunt Club, the oldest of its kind in the country. Riddle had ample room for hunting on his own property, which included a 17, 000-acre estate on Maryland's Eastern Shore as well as a 6, 000-acre farm at Glen Riddle, where he produced prizewinning livestock.
Riddle's major interest, however, was thoroughbred horses. As a young man he owned and bred a few thoroughbreds, which he raised at Glen Riddle Stables, Berlin, Maryland, and later at Faraway Farm near Lexington, Kentucky.
For a time he raced in partnership with John Howard Lewis and rode in steeplechases. He maintained a summer villa in Saratoga, New York, that for nearly fifty years was a major social center of the horse-racing set. The Riddles entertained lavishly and Samuel Riddle was renowned as a raconteur. Yankee Witch, winner of the Rosedale and Spinaway stakes in 1916, was Riddle's first thoroughbred champion. In 1918 he purchased Man o' War as a yearling from August Belmont for only $5, 000.
Man o' War's sire had been a substantial money winner, but his dam had won only one small purse. The long-legged, golden chestnut with a twenty-four-foot stride quickly established himself, under the tutelage of Riddle and his trainer Louis Feustel, as one of the fastest horses of all time.
In the 1919 and 1920 racing seasons he won twenty of twenty-one races, being defeated only in the Sanford Memorial - by a horse appropriately named Upset. (He defeated Upset handily in seven other races. ) Man o' War broke track records almost every time he ran and set three world's records. Only in his sole defeat was he pressed by another horse at the finish. Reputedly his average win was by nine-and-a-half lengths, although he carried more weight, on the average, than any horse in his age group.
Man o' War's total purse for only two years of racing was $249, 465, far more than any horse had won before 1920.
By deciding to retire Man o' War at the end of the 1920 season, Riddle aroused the ire of American horse-racing fans. He insisted that the large handicap Man o' War would have to carry as a four-year-old was unfair and might damage the great thoroughbred. Retired to stud, Man o' War produced an exceptional number of winners, despite Riddle's policy of limiting the horse's services.
In 1937 War Admiral, one of Man o' War's colts, won the Kentucky Derby, the Preakness, and the Belmont, racing's triple crown. Other notable horses in the Man o' War line included Clyde Van Dusen, Battleship, Crusader, War Glory, American Flag, Genie, and Scapa Flow.
In the 1920's and 1930's Riddle, in partnership with his nephew Walter M. Jeffords, probably produced more winners, given the size of his breeding stock, than any other thoroughbred breeder in the country.
A colorful and sometimes controversial sportsman, Riddle insisted on an exacting regimen of strict diets, exercises, and grooming and he instructed his jockeys to press their mounts only when necessary. He carefully selected the races that his horses would enter - Man o' War, for example, did not run in the Kentucky Derby or in Europe, despite tremendous public pressure. Riddle hated the handicap system.
Riddle, who died at Glen Riddle, willed most of his large estate for the establishment of a hospital in Media, Pennsylvania.
The owner of Glen Riddle Farm, Riddle bred and raced Thoroughbred race horses. His most famous horses were Man o' War and U. S. Triple Crown winner, War Admiral. He was often criticized for his management of Man o' War's stud career. If the famed horse had not been maintained largely as a private stallion, critics claimed, his siring record would have been far more impressive.
Quotations: "Now and then a horse who can't keep up with his shadow will win over a really speedy animal, because of the unfair and unintelligent distinction in the matter of weights. "
He married Elizabeth Dobson, the daughter of a textile manufacturer; they had no children.
