French corsairs now a small museum. French corsairs Corsairs () were privateers, authorized to conduct raids on shipping of a nation at war with France, on behalf of the French crown. Seized vessels and cargo were sold at auction, with the corsair captain entitled to a portion of the proceeds. Although not French Navy personnel, corsairs were considered legitimate combatants in France (and allied nations), provided the commanding officer of the vessel was in possession of a valid letter of marque ( or , the latter giving "corsairs" their name), and the officers and crew conducted themselves according to contemporary admiralty law.
Letter of marque explicit formal commission, regularly raided shipping of other nations, as in the case of Francis Drake's attacks on Spanish shipping, of which Elizabeth I (despite protestations of innocence) took a share. Grotius's 1604 seminal work on international law, "De Iure Praedae" ("Of The Law of Prize and Booty"), was an advocate's brief defending Dutch raids on Spanish and Portuguese shipping. King Henry III of England first issued what later became known as privateering commissions in 1243. These early licences were granted to specific individuals to seize the king’s enemies at sea in return for splitting the proceeds between the privateers