Magendie joined the French Royal Navy in 1781 as an apprentice, and later sailed on merchant ships, raising to second captain and distinguishing himself to the point where he was mentioned in a June 1793 meeting of the National Convention.
He was brought into Navy service with the rank of ensign and given command of a cutter patrolling off the coasts of England and Ireland.
He took part in the early stages of the Expédition d'Irlande, but on 5 January 1797, Tartu she was captured by HMS Polyphemus.
[1] Split from Régénérée by a storm, Africaine encountered HMS Phoebe, under Captain Robert Barlow, east of Gibraltar.
Phoebe, which had the weather gage, overtook Africaine and engaged her at close range, despite the French soldiers, who augmented the frigate's guns with their musket fire.
In September, he was given command of the Minerva in Napoli, sailed her to Toulon where she took the name Sibylle, and from then took part in a variety of missions.
In August 1808, by the Convention of Sintra, the defeated French troops were allowed to return to France and Magendie was ferried on HMS Nymphe.