In 1893 Lamy participated in the Le Châtelier Mission (Middle Congo) where he was in charge of studying the project of a railway between Brazzaville and the coast, and also of making botanical, geological and geographical studies. Through Alfred Le Châtelier, Lamy later met Fernand Foureau, with whom he assembled the Foureau-Lamy Mission in 1898, charged, with another two expeditions, the Gentil and Voulet-Chanoine missions, to conquer Chad and unify all French dominions in West Africa.