An Irish immigrant, a collection agent for crime bosses, a professional boxer, and a prolific gambler, John Morrissey was-if nothing else-an unlikely candidate to become one of the most important figures in the history of Thoroughbred racing. As a young man, he worked as a political heavy in New York before going to San Francisco in search of fortune at the height of the Gold Rush. After returning to the east coast, he was hired by Tammany Hall...