 Two other sources of gladiators, found increasingly during the Principate and the relatively low military activity of the Pax Romana, were slaves condemned to the arena ("damnati"), to gladiator schools or games ("ad ludum gladiatorium") as punishment for crimes, and the paid volunteers ("auctorati") who by the late Republic may have comprised approximately half – and possibly the most capable half – of all gladiators.The use of volunteers had a precedent in the Iberian "munus" of Scipio Africanus; but none of those had been paid.For the poor, and for non-citizens, enrollment in a gladiator school offered a trade, regular food, housing of sorts and a fighting chance of fame and fortune.