In 1937, while traveling by passenger liner across the Atlantic, Dupré met twenty-five-year-old Anna Stefanna Nagy who would become his second wife.

Dupré was friends with Duke Louis Decazes, a Thoroughbred racehorse enthusiast who owned the Haras d'Ouilly stud farm in Pont-d'Ouilly, Calvados.

He became one of Europe's leading breeders and owners, winning numerous important conditions races in France and England.

[2] His widow Anna ran the racing operation until 1977 when she sold the entire bloodstock for £1.3 million to the Aga Khan IV.

The Dupré's famous colors of gray with a pink cap were taken over by Jean-Luc Lagardère who would buy Haras d'Ouilly in 1981.