The Rise of the Mercenaries in the Third Century

Abstract

Foreigners joining an army for private gain are mercenaries, those doing so for political reasons are allies. By these criteria, Rome, during the Republic, used mostly allies rather than mercenaries whenever she needed foreign manpower or special fighting  skills. During the first two centuries of the Empire, when her own citizens no longer readily bore arms, Rome could rely on the plentiful supply of recruits from the provinces and client states and thus had little need for mercenaries.