Karen Stives, who helped lead the U.S. Equestrian Team to a 1984 Olympic gold medal in three-day eventing in Southern California and who just missed an individual gold medal of her own, died Aug. 14 at her home in Dover, Mass., from a rare form of cancer. She was 64.

Stives earned her place in three-day eventing history when she rode her mother’s big grey gelding, Ben Arthur, to win the individual silver at the Los Angeles Olympics. A single rail down in show jumping cost her the individual gold, but the pair’s strong finish helped earn the team gold for the U.S. Karen became the first of two women ever to win an individual Olympic three-day event medal; British rider Virginia Holgate Elliott won the individual bronze at Los Angeles.

A New England rider who rose to the top of international competition through sheer diligence, hard work, and plenty of natural ability, she was called a “small package with a thousand-pound brain,” by longtime friend and colleague, Jim Wolf. At one time she contemplated trying out for both the U.S. eventing and dressage teams in the same year — an idea she discarded after riding in two separate selection trials in the same weekend.

Stives was the USCTA Rider of Year in 1981, 1987, and 1988. She represented the U.S. in international three-day event competition on her wonderful Thoroughbred, The Saint, including the World Championships in Luhmuhlen in 1982. It was there that her mother, Lillian Mahoney, was taken by an Irish-bred horse named Ben Arthur who had been leased from a British rider by a member of the New Zealand team. Mrs. Maloney purchased him for Stives after the competition, forming a partnership that would pay off two years later in Los Angeles.

Following her retirement from international competition, Karen became an FEI judge and chair of the USET Three-Day Event Selectors’ Committee for many years. She was also one of the sport’s chief benefactors: In 2014, she donated $1 million to the USET Foundation to support the development of American riders.