A galley slave was a slave rowing in a galley, either a convicted criminal sentenced to work at the oar (French: galérien), or a kind of human chattel, often a prisoner of war, assigned to the duty of rowing. In the ancient Mediterranean, galley rowers were mostly free men, and slaves were used as rowers when manpower was in high demand. In the Middle Ages and the early modern period, convicts and prisoners of war often manned galleys, and the Barbary pirates enslaved captives as galley slaves. During the 18th and 19th centuries, pirates in Asia likewise manned their galleys with captives. Ancient Mediterranean navies relied on professional rowers to man their galleys. Slaves were seldom used except in times of pressing manpower demands or extreme emergency. In the 5th and 4th centuries BC, Athens generally followed a naval policy of enrolling citizens from the lower classes (thetes), metics (foreigners resident in Athens) and hired foreigners. In the drawn-out Second Punic War, Rome and Carthage resorted to slave rowers to some extent, but only in specific cases and often with the promise of freedom after victory was achieved. Only in the Late Middle Ages did slaves begin to be increasingly employed as rowers. It also became the custom among the Mediterranean powers to sentence condemned criminals to row in the war-galleys of the state (initially only in time of war). Traces of this practice appear in France as early as 1532, but the first legislative enactment comes in the Ordonnance d'Orléans of 1561. In 1564 Charles IX of France forbade the sentencing of prisoners to the galleys for fewer than ten years. A brand of the letters GAL identified the condemned galley-slaves. Naval forces from both Christian and Muslim countries often turned prisoners of war into galley-slaves. Thus, at the Battle of Lepanto in 1571, 12,000 Christian galley slaves were freed from the Ottoman Turks. The Knights Hospitaller made use of galley slaves and debtors (buonavoglie) to row their galleys during their rule over the Maltese Islands.