Optio

An optio was the centurion’s deputy and one of the principales of the Roman army. He assisted in running the unit and could act for an absent commander. This was a Roman military appointment, not an exact equivalent of a modern commissioned rank.

Images of optiones can show a long staff, often called a hastile. It is associated with controlling the formation; it should not be translated as an “incentive” or described as exclusively a tool for beating soldiers. The centurion’s vitis was a different object and emblem of authority.

The optio’s personal arms broadly followed those of a legionary of his period, including a gladius and dagger. Details on one tombstone do not establish a universal uniform for all optiones.

Tombstone of Publius Aelius Mestrius, optio of II Adiutrix, from Óbuda, Hungary. Hungarian National Museum, Budapest; second century CE.

Tombstone of Caecilius Avitus, optio of XX Valeria Victrix, RIB 492. Chester, Grosvenor Museum, CHEGM:1999.6.38. The inscription records fifteen years of service; no precise date is stated.

Tombstone of Monianus Capito, a naval optio associated with the ship Aurata. First century CE; evidence for naval service, not automatically a legionary centurion’s deputy.

The appointment could lead towards the centurionate: inscriptions record the formula optio ad spem ordinis, an optio awaiting promotion to centurion. This does not establish that most optiones necessarily achieved that rank or followed an identical career.

Specialist appointments using the word optio were associated with hospitals, guards and other duties. Their meaning depends on the full title and context. The number of deputies in a unit’s organisation depended on its centuries and condition, not on an unchanging total valid for the whole Roman army.

Modern reconstruction of a Roman optio; not an ancient original.

Place in the century

The optio was the closest assistant of the centurion within a century. He did not equal the centurion in rank, but he helped run the unit day to day: maintaining formation, transmitting orders, supervising discipline and assisting with administrative tasks. In battle the optio is often associated with a position behind the line, where he could keep order and push the formation forward.

This position made the optio an important link between ordinary legionaries and their commander. For understanding the Roman army, he is a useful example of how the legion depended not only on senior officers, but also on principales: experienced junior leaders who knew the men, the service and the internal order of the unit.

Equipment and signs

The most recognizable attribute of an optio in visual sources and reconstructed sets is the long staff or rod used to manage the formation and mark his position. Otherwise his equipment remained close to that of a legionary: helmet, armour, belt, sword and shield depend on period, region and specific source.

The optio was not a parade commander in luxurious equipment. What distinguished him was service function: assistance to the centurion, control of the line, transmission of orders and maintenance of order. The staff is therefore important not as decoration, but as a sign of practical authority within the formation.

Optio in the sources

The Chester tombstone of Caecilius Avitus (RIB 492) explicitly identifies him as an optio of the Twentieth Legion Valeria Victrix and records fifteen years of service. Its figure with a long staff is especially useful because the inscription establishes the appointment rather than relying on an object alone.

The Vindolanda tablet Tab.Vindol. 148, dated 97–105 CE, records a report by Candidus, optio of the century of Crescens. It directly documents an optio’s involvement in routine written reporting. Tombstones and documents complement one another without providing equally full evidence for every aspect of service.

Literature and sources

Additional views

Fragmentary tombstone of an optio awaiting promotion to centurion who died in a shipwreck. Chester, RIB 544; his name is not preserved.