Primus pilus

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The Primus pilus or Primipilus was the senior centurion of a Roman legion. [1]

Centurion professional officer of the Roman army

A centurion was a professional officer of the Roman army after the Marian reforms of 107 BC. Most centurions commanded groups of centuries of around 100 legionaries, but senior centurions commanded cohorts or took senior staff roles in their legion. Centurions were also found in the Roman navy. In the Byzantine Army, they were also known by the name kentarch. Their symbol of office was the vine staff, with which they disciplined even Roman citizens protected from other forms of beating by the Porcian Laws.

A Roman legion(romanum legio) was a large unit of the Roman army.



The literal translation of "primus pilus" is "first spear." [2] According to the Oxford Latin Dictionary, the word "pilus" when used in this sense would relate to the Latin word "pilum," or "spear" in English. [3]

Historical role

Altar dedicated to Fortuna Conservatrix by Marco Aurelio Cocceius Floriano, who was Primus Pilus of the Legio X Gemina the time of Severus Alexander in Vindobona . Weihealtar fur Fortuna Conservatrix.jpg
Altar dedicated to Fortuna Conservatrix by Marco Aurelio Cocceius Floriano, who was Primus Pilus of the Legio X Gemina the time of Severus Alexander in Vindobona .

In the late Roman republic, the cohort (of which there were between six and ten) became the basic tactical unit of the legions. The cohort was composed of five to eight centuries, each led by a centurion assisted by an optio , a soldier who could read and write. The senior centurion of the legion and commander of the first cohort was called the primus pilus, a career soldier and advisor to the legate. While every normal cohort was composed of five to eight centuries (normally six in secondus to decius cohorts), the one that was led by the primus pilus (the first) had about ten centuries, or 800 men. It also had a number of other staff, such as cooks, clerks, etc.; that is, non-combatants. In modern infantry ranks, primus pilus would be considered a Lt. Colonel in relation to battalion-size units, though there is no direct corresponding equivalent.

Cohort (military unit) Roman military unit

A cohort was a standard tactical military unit of a Roman legion, though the standard changed with time and situation, and was composed of between 360-800 soldiers. A cohort is considered to be the equivalent of a modern military battalion. The cohort replaced the maniple following the reforms attributed to Gaius Marius in 107 BC. Shortly after the military reforms of Marius, each legion formed 10 cohorts. The cohorts were named "first cohort," "second cohort" etc. The first cohort gathered the most experienced legionaries, while the legionaries in the tenth cohort were the least experienced. Until the middle of the third century AD, 10 cohorts made up a Roman legion.


An optio, plural optiones and sometimes, albeit rarely, anglicised as option – was a position in a centuria (century) of a Roman army similar to that of an executive officer. The main function of an optio was as an optio centuriae, the second-in-command of a century, although there were many other roles an optio could adopt.

<i>Legatus</i> general in the Roman army

A legatus was a high-ranking Roman military officer in the Roman Army, equivalent to a modern high-ranking general officer. Initially used to delegate power, the term became formalised under Augustus as the officer in command of a legion.

Only eight officers in a fully officered legion outranked the primus pilus: The legate ( lēgātus legiōnis ), commanding the legion; the senior tribune (tribunus laticlavus); the Camp Prefect (praefectus castrorum); and the five junior tribunes (tribūnī angusticlāviī).

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  2. Legion Organization and Ranks
  3. Souter, A., et all, ed. (1968). Oxford Latin Dictionary. ISBN   0-19-864224-5.