Lacaze was born in Pierrefonds, Oise to a physician of Réunion, where he spent his youth. He studied in France with the Jesuits, and joined the École Navale in 1879. Lacaze served as capitaine de vaisseau in Senegal, India and Viet-Nam. He was naval attaché in Rome and chief of staff to Admiral Germinet. He then took command of the Masséna, before serving as chief of cabinet to minister of the Navy Théophile Delcassé. After retiring in 1922, Lacaze was elected to the Académie française on 12 November 1936, obtaining Jules Cambon's seat (seat n°40).