Marigny founded the "Louisiana Race Course," now the Fair Grounds Race Course, with Julius C Branch and Henry Augustine Tayloe (son of John Tayloe III of the Octagon House, a leading turfman, founder of the Washington Jockey Club (1798), who imported the great English thoroughbred Diomed who sired Sir Archy-whose progeny include Lexington, Secretariat and American Pharoah; grandson of John Tayloe II who imported Childers (by Flying Childers), Jenny Cameron and Jolly Rogers (three of the most important colonial imports) and who built the grand colonial estate and stud farm Mount Airy) and organized the first races in Spring 1838, they lasted for five days.