By Paul Blake Volunteer Guide

The Roman Auxiliary Cohort - Command and Control in the 3rd and 4th centuries

During my tours as a Vindolanda guide, I often get questions about military history of the site and the relationship between different ranks in the Roman army. For example, how do a Centurion and a Prefect compare to each other? And can we equate Roman ranks and grades with contemporary examples? In this three-part blog I will explore the chain of command of an Auxiliary Cohort at Vindolanda and how control was exercised.

Part One - Command - the Cohort Prefect

By the 3rd century the prefects of auxiliary cohorts would have mostly been recruited from the Roman Equestrian Class (also sometimes referred to as knights). The command of an auxiliary cohort formed part of the tres militiae (three posts) that an equestrian had to undertake to facilitate consideration for promotion later on, either as an Imperial Administrator at high level or even as a senator. The tres militiae comprised of firstly, the command of an auxiliary infantry cohort (regiment), secondly, service as one of the six Tribunes of a Legion and finally prefect of a cavalry ala or regiment.

The period of command as an auxiliary cohort prefect was between 2 to 3 years, so we can infer that, over its near 200 years at Vindolanda, the 4th Cohort of Gauls would have been commanded by a vagary of equestrians from across the Roman Empire including Gaul. In the absence of the cohort prefect, the cohort would have been commanded by the cohort's senior centurion, the primus pilus or if he was unsuitable or unavailable by a seconded legionary centurion. There is no evidence of the latter at Vindolanda.

On appointment, it can be reasonably assumed the prefect generally would have had little ‘man management’’ leadership or command experience. He would have previously been employed in Roman administration. However, he may have come from a military family - his father may have been a legionary primus pilus (chief centurion) which on appointment automatically raised him and his family to equestrian status. Similarly, his age on appointment would have been as young as late teens, but normally mid 20s to 30.

A cohort, which the prefect presided upon, is generally regarded in modern terms as being a regiment, however it would have been of varying sizes ranging from 480 to 800 even a 1000 men with a vagary of titles to suit. Anthony Birley records the 4th Cohort of Gauls, when it arrived at Vindolanda in the second decade of the 3rd century AD, was a unit of a paper strength of 480 infantry and 120 cavalry which would have made it a cohors equitata. Whether or not the cavalry element remained in the cohort throughout its garrisoning is uncertain. During the reign of Emperor Diocletian (284-305), the Army undertook radical restructuring and during that period the fort was struck and rebuilt probably with a reduction in cohorts infantry strength but certainly with the addition of higher grade cavalry elements, as was revealed in the excavations of 2017-20. A prefect could therefore have had under his command as many as 6 infantry centuries (companies) of 80 men, each commanded by a centurion and 120 cavalry formed into 4 turmae (troops) commanded by decurions, the cavalry equivalent of centurions.

As the visitor to Vindolanda will see, the praetorium (commanding officer’s residence) accorded to the newly arrived prefect is palatial, particularly when comparing it to the 8 man contubernium (section) accommodated in 2 small adjoining rooms or even the ‘two up two down’ houses of the centurions. He will be accompanied usually by his wife and family, possibly younger teenage female Equestrians’ as ‘ladies in waiting’ to the now First Lady of the garrison and a suitable retinue of servants and slaves. The posting to Britannia Inferior would probably not have been the first choice of the aspiring prefect. However, given the pay and the efficiency of the Roman logistical organisation, materially they wanted for nothing for their short duration at Vindolanda. This is demonstrated still today by the excavations within the fort wall, which produce some of the amazing finds displayed in the Museum.

If we compare a cohort to a modern regiment then the prefect would equate to a Colonel, a rank which in modern terms can only be achieved by at least 30 years’ service. This might sound strange, but we must remember that, even in the British army, from its mid-17th century conception and up until the reforms of Cardwell in the late 19th century, nobility and landed gentry with no real prior military experience still formed their own regiments and appointed themselves its Colonels.

The interaction between the newly arrived prefect and the centurions is best described with a modern comparison. In the British Army, a newly commissioned ‘one pip’ 2nd lieutenant will, on arrival in his regiment, be placed in command of a platoon or troop of up to 40 men. His immediate subordinate will be the troop/platoon Sergeant or Staff Sergeant, who will have probably 15 years’ experience over his new young officer. The two may or may not take an immediate dislike to each other, but both are aware they have their own careers to consider. Quite simply, they have to get on. As an officer cadet at Sandhurst, the higher-ranking man would have been instructed by Senior NCOs. Now, as a commissioned lieutenant, he gives the orders and the SNCO will interpret them and ensure compliance.

Command is exercised by the Prefect by his right of authority but very much by the compliance and co-operation of his centurions the majority of which will have 15-20 years military experience and possibly depending on means of achieving the rank between 5-20 years in the status of this rank. Nothing therefore, in command and control regards has changed since the Roman occupation. Now that we have discussed the figure of the Prefect, the status of the centurions will be explored in the second part of this blog.

This blog has been written as part of our Roman Holiday Project.  


P A Holder - The Roman Army in Britain

Graham Webster - The Roman Imperial Army

Adrian Goldsworthy - The Complete Roman Army

Anthony Birley - Garrison Life at Vindolanda

Robin Birley - Vindolanda

Further Reading

David Divine - Hadrian's Wall - the NW Frontier of Rome

Adrian Goldsworthy - Hadrian’s Wall

Paul Elliott - Every Day life of a Soldier on Hadrian’s Wall

Guy De La Bedoyere - Gladius - Living, Fighting and Dying in the Roman Army