The Haras d'Ouilly is a renowned horse breeding farm in Pont-d'Ouilly, Calvados in the Normandy region of France established in the 19th century.
He acquired several top broodmares and in 1918 purchased the prominent sire Prince Palatine from the English breeder Jack Barnato Joel.
In 1921 Decazes partnered with François Dupré who would purchase 100% of Haras d'Ouilly in 1930.
François Dupré would turn Haras d'Ouilly into a powerhouse of European racing, running it until his death in 1966 when his widow took over.
Anna Dupré continued to race horses until 1977 when she sold her bloodstock to the Aga Khan IV.