Proteau was born on the island of Groix in Morbihan in 1772 and joined the French Navy after the French Revolution in 1793. In December 1796 he served with the fleet which participated in the Expédition d'Irlande, a failed attempt to invade the Kingdom of Ireland with an army led by Lazare Hoche as Lieutenant on a ship named "l'Aigle", and was made a prisoner at Bantry.