In 1919, Man o' War won 9 of 10 starts including the Hopeful Stakes and Belmont Futurity, then the most important races for two-year-old horses in the United States.His only loss came at Saratoga Race Course, later nicknamed the Graveyard of Champions, where he had a poor start and was beaten by a colt fittingly named Upset.
He had a slightly Roman nose and notably high head carriage.His nickname was "Big Red", though his coat had tinges of yellow and gold.Riddle originally intended to race Man o' War in 1921 but decided against it because Man o' War would have been assigned record weights in the handicap format used in races for older horses.Instead, Man o' War was retired to stud, where he became a leading sire whose multiple champions included Triple Crown winner War Admiral.He was inducted into the National Museum of Racing and Hall of Fame in 1957.
On March 29, 2017, the museum opened a special exhibit in his honor, "Man o' War at 100".
He typically won in front-running fashion and was only closely pushed in two of his starts.
He won the Belmont Stakes by twenty lengths and the Lawrence Realization by a hundred.
Man o' War was not entered in the 1920 Kentucky Derby because his owner, Samuel Riddle, did not believe in racing at the distance of 10 furlongs so early in a young horse's career.
Instead, Man o' War made his three-year-old debut in the Preakness Stakes where he defeated Upset by lengths.
joined the United States Army at age 65 to serve in France during World War I.