In 1765, Commerson was invited to join Bougainville's expedition. He hesitated in accepting because he was often in poor health; he required Baret's assistance as a nurse as well as in running his household and managing his collections and papers. His appointment allowed him a servant, paid as a royal expense, but women were completely prohibited on French navy ships at this time. At some point, the idea of Baret disguising herself as a man in order to accompany Commerson was conceived. To avoid scrutiny, she was to join the expedition immediately before the ship sailed, pretending to be a stranger to Commerson.