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.

Let’s travel back in time and imagine the scene: The centurion, considered by his soldiers akin in power to a demigod, strides intently across the parade ground at Vindolanda towards the awaiting cohorts 1st century paraded to his front. His Gallic helmet is adorned with a transversely mounted crest, his mail body armour has a leather harness on top to support the decorations and awards for his service, he wears his sword to the left, a dagger to the right and carries a vine stick in his right hand, symbols of his rank and position for this demigod is the senior centurion of the 4th Cohort of Gauls.

In contemporary terms it was easy to describe the prefect of the cohort; he is their Colonel. In Roman terms, there is just one rank - centurion, but that rank is graded by seniority and appointment. The six centurions of the auxiliary cohort were in ascending order titled hastatus posterior, hastatus prior, princeps posterior, princeps prior, pilus posterior and pilus prior or princeps. We have therefore identified an order of seniority as centurions - collectively known as the centurionate.

The princeps is the senior and by appointment, the second in command at Vindolanda. He will have been a centurion for as long as two decades and is highly experienced. The hastatus posterior however, may be newly appointed and a centurion for just a year or so. Irrespective of their seniority in the centurionate, almost all of the centurions of the cohort would have served time in the ranks of a cohort passing through the non-commissioned ranks to achieve the officer grade of centurion. That time would have ranged from 10 to 20 years depending on ability and availability. It was possible for a recommended legionary soldier to transfer to an auxiliary cohort as a duplicareus and after a period in command of men commissioned into the centurionate. Similarly, it is known that equestrians unable to obtain legionary commissions joined auxiliary cohorts - there is no evidence of either at Vindolanda however.

The title of centurion covers numerous modern ranks. It is perhaps best to see that the centurion is ‘captain’ of his century, especially considering the ancient title of captain as given to trained bands of men in medieval Europe.  The princeps, whose role placed him as the cohort’s second in command, would have been being a grade higher than the captain, perhaps a modern major.

The centurion in the infantry is chosen for his size, strength and dexterity in throwing his missile weapons and for his skill in the use of his sword and shield; in short for his expertness in all the exercises. He is to be vigilant, temperate, active and readier to execute the orders he receives than to talk; Strict in exercising and keeping up proper discipline among his soldiers, in obliging them to appear clean and well-dressed and to have their weapons constantly rubbed and bright.” Vegetius, 4th century

In essence, the centurion (even of an auxiliary cohort) had great status and power over his command. As a senior centurion, he would be entrusted with vexillations (detachments) away from the fort where he would have arbitrarily exercised both command and control. His badge of office, the vine stick, had yet another purpose: it was a means to ‘chastise’ the petty offender. He would have used his junior officers to exercise his authority and ensure the century performed effectively and to the satisfaction of the prefect whilst ensuring his peers maintained their centuries to his high standards.

Vegetius remarks as to strength, size and dexterity are most relevant as in the field the centurion commanded his century from the front rank in attack and/or defence and, wearing his gleaming armour, he would have attracted attention from the enemy. Similarly, his personal ability in close order contact and combat would have to be that of great strength and ability to ensure the cohesion of his men.

At Vindolanda the centurions were accommodated in their personal double story 4 room house, attached to the barrack block containing the contubernium rooms of his men. Unlike his men, the centurion would have been permitted by the law to marry or have a common law wife. He would have most likely had a servant or slave and certainly a horse. He could expect to dine with the non-executive cohort officers in their mess but equally would have been invited to dine with the prefect and presented to visiting dignitaries and commanders.

We can see that with and on behalf of the prefect, the centurions effectively commanded the cohort. However, control was also delegated by the centurions to the junior officers. We’ll talk about this in part 3.

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