A government mission to the French colonies in 1886-1887, in connection with the approaching Paris exhibition, gave him the opportunity of studying colonial questions, on which, after his return, he published three works: "La Tunisie" (Paris, 1887); "L'Expansion coloniale de la France" (ib., 1888), "L'Indo-Chine francaise" (ib., 1889). In 1891 he was made civil and military governor of French Indochina, where his administration, which led to open rupture with Admiral Fournier, was severely criticized. Nevertheless, he consolidated French influence in Annam and Cambodia, and secured a large accession of territory on the Mekong River from the kingdom of Siam. He was recalled in 1894, and published an apology for his administration ("La Colonisation francaise en Indo-Chine") in the following year.