Ternay, having obtained the position of governor of Île de France (Mauritius), will not forget his protégé and will take him with him. Louis XV had recently decided to take back the direct administration of the support base in the Indian Ocean, given that the Compagnie des Indes was not able to support this expense. Lapérouse will become acclimated to this new environment as a second captain on a governmental Store ship carrying local goods in the southern Indian Ocean, the same period in which he will meet his future wife when his ship calls at Vieux Grand Port (Mauritius). Then Ternay gives him command of the military barge La Seine, on which he carries out two campaigns in the Indiesone on the east coast of Pondichery at Chandemagor (Calcutta), the other on the west coast as north as Surate.
It is during the course of this second voyage that Lapérouse will have the opportunity to win a real military victory, by defending brilliantly, with meager resources, the French territory at Mahé against an attack by Indianssupposedly friendly to the Frenchto whom he had been directed several months earlier to deliver arms. This victory will earn him the Croix de St. Louis on his return to France. During his stay at Île de France, he takes note of the explorations of Grenier, Kerguelen, and Saint-Allouam, then of Cook during his second voyage as well as the occupation of Madagascar by Beniowki. During a last and fifth year on land in the services of the Navy at Port Louis (Mauritius), he deepens his relationship with Ėléonore, whom he receives at his new property, Eau Coulée, but his parents temporarily veto a possible marriage. He will learn a lot during this stay about the colonial system of the period, international agreements, and overseas tradethe source of riches and world control. These preoccupations with global matters distance him more and more from those of his parents, adding to the conflict over their refusal of a marriage of love. As soon as he returns to France, he is promoted, in 1777 at the age of 35, to the rank of ship’s lieutenant.