top of page
  • Writer's pictureTastes Of History

A Century equals Eighty?

Updated: Feb 16

With the title ‘5 Facts You DIDN’T KNOW About The Romans’ a recent YouTube video sounded intriguing. In ascending order, the first fact, number five beginning at 45 seconds, introduces the idea that a centurion commands 100 men but then states that if you research the Roman army you will discover a century was only 80 strong. This is indeed the case, but the fact ‘you didn’t know’ was that a century was indeed 80 soldiers, but 100 men. The argument goes that a contubernium of eight soldiers included two often forgotten or unmentioned slaves. In other words, a century comprising ten contubernia equals 80 soldiers plus 20 slaves for a total of 100 men. Unfortunately, in this two-minute segment no references were provided, so we thought we would have a look.

Definitions First stop, Wikipedia. The entry for ‘Contubernium (Roman Army Unit)’ is largely based on an article published on the ThoughtCo website written by NS Gill, an ancient history and Latin expert from Minnesota, USA. Under the subtitle ‘Contubernium of Soldiers in the Roman Army’ her entry reads (Gill, 2018):

‘There was one leather sleeping tent to cover a group of eight legionaries. This smallest military group was referred to as a contubernium and the eight men were contubernales [1]. Each contubernium had a mule to carry the tent and two support troops. Ten such groups made up a century. Every soldier carried two stakes and digging tools so they could set up camp each night. There would also be enslaved people associated with each cohort. Military historian Jonathan Roth [2] estimated there were two calones or enslaved people associated with each contubernium.’

For those unfamiliar with the Latin terms or Roman military organisation, then some explanation is in order. Firstly, according to William Smith’s ‘A Dictionary of Greek and Roman Antiquities’:

‘…in its original meaning, contubernales (σύσκηνοι) signified men who served in the same army and lived in the same tent. The term is derived from taberna, which, according to Festus, was the original name for a military tent as it was made of boards (tabulae). Each tent was occupied by ten soldiers (contubernales), with a subordinate officer at their head, who was called decanus, and in later times caput contubernii (Vegetius, Epitoma Rei Militaris, II.8, 13; cf. Cicero, pro Q. Ligario oratio, 7; Hirtius, De Bello Alexdrino, 16)’ (Smith, 1875, s.v.).

Interestingly Smith refers to ‘ten soldiers’ (our emphasis above) led by a decanus, a ‘chief of ten’ in late Latin. Today we might presume a decanus was a non-commissioned officer (NCO) but the rank structure in the Roman army does not equate to current models. A decanus was more likely the senior or longest serving soldier in the conturbernium. Smith’s definition makes no reference to servants or slaves. Yet Gill cites Roth to introduce two calones, a term derived from Latin calo ‘a servant in the army, soldier's servant’ (Lewis and Short, 1879). Was Smith correct or is the answer Roth’s estimated addition of two slaves per conturbnium of eight soldiers. Frustratingly, most contemporary definitions of the conturbernium include the eight soldiers but make no mention of two calones. Yet, as Smith definition of calones bears out, they clearly existed from the accounts of ancient authors such as Festus, Servius and Gaius Julius Caesar himself:

‘…the servants of the Roman soldiers, said to have been so called from carrying wood (κᾶλα) for their use (Festus, s.v.; Serv. ad Virg. Aen. VI.1). They are generally supposed to have been slaves, and they almost formed a part of the army, as we may learn from many passages in Caesar: in fact, we are told by Josephus that, from away living with the soldiers and being present at their exercises, they were inferior to them alone in skill and valour…The word calo, however, was also applied to farm-servants.’ (Smith, 1875, s.v.)

So, despite evidence for two slave/servants per contubermium, modern descriptions of the Roman army ignore them in favour of the 80-soldier Century typical of the early Imperial period, or Principate, onward. If, however, we travel back into Roman military history, then we do find evidence for a Century being 100 strong.

Centuria The Roman Century, or centuria, is derived from the Latin word centum meaning ‘one hundred’. Yet, as with most words, there is more than one sense in which centuria can be used. In military parlance it was a division of Roman infantry, the smallest tactical unit of a legion. According to Lewis and Short’s 1879 ‘Latin Dictionary’ the term centuria also meant:

  • An assemblage or a division consisting of a hundred things of a kind; hence in general any division, even if it did not consist of a hundred.

  • A unit of area, specifically in agriculture where it represented a number of acres.

  • One of the one hundred and ninety-three orders (‘centuries’) into which the second Etruscan king, Servius Tullius, divided the Roman people according to value of their property. The assemblies in which the people voted according to centuries were called comitia centuriata.

The latter definition is significant because it gives a clue how the centuries in the Roman army were originally of 100 men and why, even when later they varied between 60 and 160 men, the term ‘century’ continued to be applied.

The Etrusco-Roman Army The early Roman army (Latin: exercitus Romanus) of the Roman Kingdom and of the early Roman Republic was based on an annual levy. The army consisted of 3,000 infantrymen and 300 cavalrymen, the latter all being drawn from the wealthiest social class known as equites, the ‘equestrians’. The Latin, Sabine and Etruscan tribes under the Roman command would each provide an extra 1,000 soldiers and 100 cavalrymen. At this time, when warfare chiefly consisted of small-scale plundering raids, it has been suggested that the army followed Etruscan or Greek models of organisation and equipment.

While much of Roman history of this period is founded on legends, during the reign of Servius Tullius, the army was reformed or, rather, refined. Accordingly, all healthy, property-owning male Roman citizens were divided into five distinct classes for military service, from the poorest in the ‘fifth class’ to the richest in the ‘first class and the equestrians above them’. This socio-economic class system was based on the individual's wealth since soldiers had to provide their own weapons and equipment. The highest social class, the equestrians, continued to serve in the mounted cavalry units known as equites. The five other classes were organised, according to their voting tribe, into infantry units of 100 men called centuria (‘centuries’). Presumably the commanders of these centuria where the centuriones (‘centurions’). If so, then the first centurions did indeed command 100 soldiers as the name implies.

At first there were only four Roman legions (Latin: legio (pl. legiones); from legere (‘to choose; to collect’). The term legio therefore has the meaning of a selection or chosen body of men; hence it is often described as a levy. These legions were numbered ‘I’ to ‘IIII’, where first legion was seen as the most prestigious and fourth was not written ‘IV’. The bulk of this army was made up of Roman citizens. These citizens could not choose the legion to which they were allocated, however. Any man ‘from ages 16 to 46 were selected by ballot’ and assigned to a legion.

Mid-Republic At some point, possibly in the beginning of the Roman Republic after the kings were overthrown, the legio (or ‘levy’) was subdivided into two separate legions each commanded by one of the two annually elected Consuls who controlled Roman affairs. In the first years of the Republic, when warfare consisted of mostly raids, it is uncertain if the full manpower of these legions was ever summoned at one time. The legions became organised in a more formal way in the 4th-century BC, as the Roman method of waging war evolved into more frequent and planned operations, and each consular army was increased to two legions. In the Republic, however, these legions had a short-lived existence. Excepting Legions I to IV that formed the consular army (i.e. two per Consul), other units were levied according to the needs of the campaign. At the same time, Rome's Italian allies were required to provide a legion in support of each Roman legion.

The Manipular Legion With the appearance of the military tribunes after 331 BC (at first these tribunes took turns as the legion's commanding officer) the internal organisation of the legion became more sophisticated. The developments from the classic phalanx to the ‘manipular’ system also allowed important tactical innovations. More importantly, for the first time, the classes of soldiers who comprised the legions were based on experience and age rather than wealth, with standard weapons and equipment issued by the state. In the middle years of the Republic, the Roman army was organised into three lines, the Hastatii, the Principes, and the Triarii. Each of these three lines was subdivided into maniples of 120, 120 and 60 men, respectively. A full legion, therefore, still fielded about 3,000 men.

The maniples each consisted of two centuriae (centuries) and each maniple was commanded by the senior of the two centurions. Centuries were nominally 80 soldiers strong (not the expected 100 of the earlier levy), but in practice might be as few as 60, especially in the less numerous maniples of Triarii. Each century had its own standard and, as before, comprised ten contubernia.

And finally Although the army continued to evolve, the century system endured. Thus, throughout the Principate the 80-man century persisted to eventually become one of those well-known, but seemingly contradictory, facts. Centurions, therefore, certainly commanded 80 fighting men but as allude to by our ancient authors, they also were responsible for at least a further 20 calones. Thus Centurions were responsible for a total strength appropriate to any definition of their rank, 100 men.



1. In a wider sense, the name contubernales was applied to any persons connected by ties of intimate friendship and living under the same roof.

2. Roth, J., (1994), ‘The Size and Organization of the Roman Imperial Legion’, Historia: Zeitschrift für Alte Geschichte, Vol. 43, No. 3 (3rd Qtr., 1994), pp. 346-362.


Gill, N.S., (2018), ‘The Roman Army of the Roman Republic’, ThoughtCo., Available on-line: (accessed 12 October 2021).

Lewis, C.T. and Short, C., (1879), A Latin Dictionary, s.v. ‘calo’, Oxford: Clarendon Press.

Smith, W., (1875), ‘A Dictionary of Greek and Roman Antiquities’, s.v. ‘Conturbernales’, London: John Murray.

Ancient sources:

Publius (or Flavius) Vegetius Renatus, Epitoma Rei Militaris Liber II (‘Concerning Military Matters Book II’), LacusCurtius, Available online (accessed 12 October 2021).

Marcus Tullius Cicero, pro Q. Ligario oratio (‘Oration in defence of Quintus Ligarius’), LacusCurtius, Available online (accessed 12 October 2021).

Sextus Pompeius Festus, De verborum significatione libri XX ('Twenty Books on the Meaning of Words'),

Aulus Hirtius, De Bello Alexandrino (‘the Alexandrian War’), LacusCurtius, Available online (accessed 12 October 2021).

Maurus Servius Honoratus, In Vergilii Aeneidem commentarii (‘Commentary on the Aeneid of Vergil’), LacusCurtius, Available online (accessed 14 October 2021).


Recent Posts

See All


bottom of page