What is "gallahadion"

Gallahadion (March 31, 1937 – July 7, 1958) was an American Thoroughbred racehorse best known as the 1940 winner of the Kentucky Derby. He was a son of the Champion sire Sir Gallahad III, and his damsire was U.S. Horse of the Year Reigh Count, who won the 1928 Kentucky Derby. Owned by Ethel V. Mars' Milky Way Farm, named for her company's famous chocolate bar brand, Gallahadion raced at age three in California. Although he was unplaced in the Santa Anita Derby and the San Juan Capistrano Handicap, after winning the 1940 San Vicente Stakes and finishing second in the Derby Trial, Gallahadion was entered in the Kentucky Derby.