A decurion (

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

: ''decurio'', plural ''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 wit ...

officer in command of a squadron (''

turma A ''turma'' (Latin for "swarm, squadron", plural ''turmae''), (Greek: τούρμα) 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 ...

'') of cavalrymen in the

Roman army The Roman army (Latin: ) was the armed forces deployed by the Romans throughout the duration of Ancient Rome, from the Roman Kingdom (c. 500 BC) to the Roman Republic (500–31 BC) and the Roman Empire (31 BC–395 AD), and its medieval contin ...

Republican army

During the

Roman Republic The Roman Republic ( la, Res publica Romana ) was a form of government of Rome and the era of the classical Roman civilization when it was run through public representation of the Roman people. Beginning with the overthrow of the Roman Kin ...

a "Polybian"

legion Legion may refer to: Military * Roman legion, the basic military unit of the ancient Roman army * Spanish Legion, an elite military unit within the Spanish Army * Legion of the United States, a reorganization of the United States Army from 179 ...

(c. 300–88 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'' literally means "leader of ten men", 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 about 30 BC to 476 AD, and the final incarnation in the long history of the Roman army. This period is sometimes split into the Principate (30 BC – 284 AD) and the Do ...

of the

Principate The Principate is the name sometimes given to the first period 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 so-called Dominate. ...

(30 BC – AD 284), a decurion also commanded a cavalry ''turma'' of c. 30 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

, which contained c. 5,600 men, contained a small cavalry arm of just 120 men (i.e., four ''turmae''). Since the average number of legions deployed was c. 30, imperial legionary cavalry numbered only c. 3,600, out of a total of c. 80,000 cavalrymen deployed by the imperial army. There were thus c. 120 cavalry decurions in the legions at any given time. The vast majority of the imperial cavalry was in the regiments of the

auxilia The (, lit. "auxiliaries") were introduced as non-citizen troops attached to the citizen legions by Augustus after his reorganisation of the Imperial Roman army from 30 BC. By the 2nd century, the Auxilia contained the same number of inf ...

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

Roman citizen Citizenship in ancient Rome (Latin: ''civitas'') 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, t ...

ship (known as ''

peregrini In the early Roman Empire, from 30 BC to AD 212, a ''peregrinus'' (Latin: ) 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 centur ...

''). An ''

ala Ala, ALA, Alaa or Alae may refer to: Places * Ala, Hiiu County, Estonia, a village * Ala, Valga County, Estonia, a village * Ala, Alappuzha, Kerala, India, a village * Ala, Iran, a village in Semnan Province * Ala, Gotland, Sweden * Alad, S ...

'' (literally "wing"), 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''). ''Circa'' 90 ''alae'' were deployed in the time of emperor

Hadrian Hadrian (; la, Caesar Trâiānus Hadriānus ; 24 January 76 – 10 July 138) was Roman emperor from 117 to 138. He was born in Italica (close to modern Santiponce in Spain), a Roman ''municipium'' founded by Italic settlers in Hispania B ...

(ruled 117–138). In addition, the auxiliary corps included a type of regiment known as a ''

cohors equitata A cohort (from the Latin ''cohors'', plural ''cohortes'', see wikt:cohors for full inflection table) was a standard tactical military unit of a Roman legion. Although the standard size changed with time and situation, it was generally compos ...

'', 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 c. 2,500 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