Dupré served in the French Army during World War I. Seriously wounded during battle, he was hospitalized for a considerable length of time. He went on to a career in business that saw him become the owner of two luxury hotels in Paris, the prestigious Hotel George V, Paris and the Hotel Plaza Athenée. In addition, in 1947, Dupré acquired the Hotel Ritz in Montreal, Canada. 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.