A decurion (

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

: ''decurio''; : ''decuriones'') was a

Roman cavalry Roman cavalry (Latin: ''equites Romani'') refers to the horse-mounted forces of the Roman army throughout the regal, republican, and imperial eras. In the regal era, the Roman cavalry was a group of 300 soldiers called ''celeres'', tasked wi ...

officer in command of a squadron (''

turma A ''turma'' (; plural ''turmae''; ) was a cavalry unit in the Roman army of the Republic and Empire. In the Byzantine Empire, it became applied to the larger, regiment-sized military-administrative divisions of a '' thema''. The word is often tran ...

'') of cavalrymen in the

Roman army The Roman army () served ancient Rome and the Roman people, enduring through the Roman Kingdom (753–509 BC), the Roman Republic (509–27 BC), and the Roman Empire (27 BC–AD 1453), including the Western Roman Empire (collapsed Fall of the W ...

Republican army

During the

Roman Republic The Roman Republic ( ) was the era of Ancient Rome, classical Roman civilisation beginning with Overthrow of the Roman monarchy, the overthrow of the Roman Kingdom (traditionally dated to 509 BC) and ending in 27 BC with the establis ...

a "Polybian" legion ( BC) of citizen-levies had a cavalry complement of 300 horse, divided into 10 ''turmae'' (squadrons) of 30 men each. Each ''turma'' was led by three decurions, who were elected by the squadron members themselves. Although ''decurio'' (), it does not appear that a ''turma'' was sub-divided into three troops of ten men each. Instead, one decurion would act as squadron commander and the other two as his deputies.Polybius VI.25

Imperial army

In the

Imperial Roman army The Imperial Roman Army was the military land force of the Roman Empire from 27 BC to 476 AD, and the final incarnation in the long history of the Roman army. This period is sometimes split into the Principate (27 BC – 284 AD) and the Dominate ...

of the

Principate The Principate was the form of imperial government of the Roman Empire from the beginning of the reign of Augustus in 27 BC to the end of the Crisis of the Third Century in AD 284, after which it evolved into the Dominate. The principate was ch ...

(30 BC – AD 284), a decurion also commanded a cavalry ''turma'' of men, but now without colleagues. In common with all soldiers in the imperial army, decurions were long-service professionals, the majority volunteers. A Roman imperial legion, which contained men, contained a small cavalry arm of just 120 men (i.e., four ''turmae''). Since the average number of legions deployed was , imperial legionary cavalry numbered only , out of a total of cavalrymen deployed by the imperial army. There were thus cavalry decurions in the legions at any given time. The vast majority of the imperial cavalry was in the regiments of the ''

auxilia The (; ) were introduced as non-citizen troops attached to the citizen Roman legion, legions by Augustus after his reorganisation of the Imperial Roman army from 27 BC. By the 2nd century, the contained the same number of infantry as the ...

'', the non-citizen corps of the regular imperial army (whose recruits were mainly imperial subjects who did not hold

Roman citizenship Citizenship in ancient Rome () was a privileged political and legal status afforded to free individuals with respect to laws, property, and governance. Citizenship in ancient Rome was complex and based upon many different laws, traditions, and cu ...

(known as ''

peregrini In the early Roman Empire, from 30 BC to AD 212, a ''peregrinus'' () was a free provincial subject of the Empire who was not a Roman citizen. ''Peregrini'' constituted the vast majority of the Empire's inhabitants in the 1st and 2nd centuries AD. ...

''). An '' ala'' (), which was an elite all-cavalry regiment, contained 480 horse (16 ''turmae'', thus 16 decurions). A double-strength ''ala'' (''ala milliaria'') contained 720 horse (24 ''turmae''). ''alae'' were deployed in the time of emperor

Hadrian Hadrian ( ; ; 24 January 76 – 10 July 138) was Roman emperor from 117 to 138. Hadrian was born in Italica, close to modern Seville in Spain, an Italic peoples, Italic settlement in Hispania Baetica; his branch of the Aelia gens, Aelia '' ...

(ruled 117–138). In addition, the auxiliary corps included a type of regiment known as a '' cohors equitata'', an infantry unit with a cavalry complement of 120 horse (4 ''turmae''; 8 in a double-strength unit). Around 180 such regiments existed under Hadrian. There were thus decurions serving in the auxilia at any given time. In the imperial period, decurions were no longer conscripted Romans, commoners who were often promoted from the ranks, but could also be members of native tribal aristocracies. (Roman knights at this stage only provided the overall commanders ('' praefecti'') of the

ry regiments.) Thus, decurions in the imperial army were of far lower social status than their predecessors in the Republican cavalry. The latter were not only Roman citizens, but also aristocrats, whereas auxiliary decurions were mostly commoners and non-citizens (until AD 212, when all imperial subjects were granted citizenship). Even if they belonged to a native aristocracy, they ranked lower than a commoner Roman citizen in the status-conscious Roman empire.

References

Literature

* {{DEFAULTSORT:Decurion (Military) Ancient Roman titles Military ranks of ancient Rome