Man o' War made his last public appearance in racing colors on January 28, 1921, when he was cantered past fans at the Kentucky Association track in Lexington, Kentucky, and then went to the Hinata Stock Farm near Lexington to begin life as a stud in the care of Miss Elizabeth Daingerfield. He proved almost as successful as a sire as he had been on the race track, passing his talent to his descendants in unusual fashion: of his 379 named foals, 291 raced and 64 became stakes winners, or 17 percent, and of his first 90 foals, 26 were stakes winners, or 29 percent, far above the breed average of about three percent. This record was achieved despite his being bred to no more than 25 mares in a season, so that his total of 379 named foals in 22 seasons at stud was less than a horse of his quality would produce today, and despite mares described as mostly nondescript and singularly undistinguished. Man o' War became America's leading sire in 1926 when his racing progeny earned a then-record $408,137. His best son was the champion War Admiral, winner of the Triple Crown in 1937 and later America's leading sire in 1945. Other champions he sired included American Flag, Crusader, Bateau, Scapa Flow, Edith Cavell, Maid at Arms, and Florence Nightingale. His chestnut son Battleship was a stakes winner on the flat and, after being trained over jumps, won the Grand National Steeplechase at Belmont Park; two years later Battleship became the first American-owned and American-bred winner of the Aintree Grand National in England. Man o' War also sired Blockade, a three-time winner of the Maryland Hunt Cup, and Holystpne, a champion show jumper. Remembered as both a champion racehorse and a sire of champions, he was praised by Joe Palmer as a horse of extraordinary power and singular greatness.