Once his studies were completed, peace had returned to France, and jobs in the Navy were scarce. Lapérouse sailed the French Atlantic coast carrying timber between Bayonne and the shipyards of Rochefort and Brest, thus participating in the reconstruction of the French fleet after the war.
In 1772, the Chevalier de Ternay was appointed Governor of Île-de-France, today Mauritius: his protégé, Lapérouse, accompanied him. From Port-Louis d’Île-de-France, Lapérouse carried out numerous supply missions in the Indian Ocean on board L’Africain. In 1773, Ternay entrusted him with the command of the ship La Seine, with which he undertook two expeditions to India, the second of which earned him the Cross of Saint Louis on his return to France.
On the Island of France, Lapérouse met Éléonore Broudou, daughter of an island official. Because of the latter’s bourgeois background, Laperouse’s father, Victor-Joseph de Galaup, opposed their marriage – it was not until ten years later, in 1783, that Laperouse married Eleonore, in Paris, after their story had undergone many twists and turns. Lapérouse did not return to France until 1777, one year before France went to war against England on the side of the insurgent colonists in America. He then joined the fighting, commanding the frigate Amazone, with the fleet commanded by the Count of Estaing. Then, under the command of Ternay, he took command of the frigate L’Astrée, and finally joined the command of Admiral de Grasse, before being promoted to captain in 1781 on the occasion of the battle of Louisbourg.