In the early Roman republic the infantry provided by the allies were organized in separate cohortes of varying strength, each under a Roman or native *praefectus. In the legions the cohort was first used as a tactical unit by P. *Cornelius Scipio Africanus in Spain, but for over a century it was employed alongside the manipular organization (see manipulus) before the latter was superseded in the field (perhaps in the Marian period). The cohort was made up of three maniples, or six centuries, the latter retaining manipular titulature into the Tetrarchic period. There were ten cohortes in a legion.From the time of P. *Cornelius Scipio Aemilianus, the general's personal bodyguard was known as the cohors praetoria. By the middle of the 1st cent. bce, the term was used also to describe the group of personal friends and acquaintances which accompanied a provincial governor. Both these usages led to developments in the empire. This entourage was the origin of the emperor's cohors amicorum (see amicus augusti); the military cohortes praetoriae were formalized in the praetorian guard (see praetorians).