Caucasus (14 May 1972 – after 1991) was an American-bred Thoroughbred racehorse and sire who won major races on both sides of the Atlantic. As a young horse he was sent to race in Ireland where he won four of his five races as a three-year-old in 1975 including the Ulster Derby and Irish St. Leger. He then returned to America where he had considerable success in the next two years, winning five races including the Sunset Handicap, Manhattan Handicap, Arcadia Handicap and San Luis Rey Handicap. He had some success as a breeding stallion. Background Caucasus was a bay horse with a white star and a white sock on his right hind leg bred in Kentucky by his owner Jane Engelhard's Cragwood Estates. He was sent to race in Europe and entered training with Vincent O'Brien at Ballydoyle. He was from the first crop of foals sired by Nijinsky, a Canadian horse who won the Triple Crown in 1970. During his racing career Nijinsky had been trained by O'Brien and owned by Jane Engelhard's husband Charles (1917–1971). Caucasus's dam Quill was a top-class racehorse who was named American Champion two-year-old filly in 1958 before going on to win the Acorn Stakes and Mother Goose Stakes in the following year. As a broodmare, her other descendants have included Run the Gantlet and Awesome Feather. Racing career 1975: three-year-old season Caucasus made a successful racecourse debut in a maiden race over ten furlongs at Phoenix Park Racecourse and followed up in a handicap over one and a half miles at the Curragh. In June he was sent to Northern Ireland for the Ulster Derby at Down Royal and won his third consecutive start. In August he was sent to England for the March Stakes (a trial for the St Leger Stakes) over fourteen furlongs at Goodwood Racecourse. He started odds-on favourite but after being retrained towards the rear of the field he failed to overhaul Whip It Quick and finished second, beaten half a length by the winner. On 20 September Caucasus equipped with blinkers when he was moved up in class for the Group 1 Irish St. Leger over fourteen furlongs at the Curragh. Ridden by Lester Piggott he started the 3/1 second favourite behind Nuthatch (winner of the Nijinsky Stakes) while the other eleven runners included Shantallah (Chester Vase), Music Ville (fourth in the Irish Oaks), Sir Daniel and