Imperial Roman Army – Recruitment


The Imperial Roman Army has been and is still admired by many people as an excellent fighting force. There are many reasons why the Roman Army was so effective, one was its recruitment process (probatio) which consisted in determining if a potential recruit fulfilled the necessary criteria to serve in the Imperial Roman Army.


There were physical, mental and legal requirements for joining the Imperial Roman Army. Note that the requirements were the highest for elite units like the Praetorians and Legionaries.

Physical Requirements


Let’s start with the physical requirements a soldier needed to be of a certain height. The values for a Legion soldier were at least 1.72m or 5ft 8 inches in height. For soldiers of the first cohort or cavalry even up to 1.78m or 5ft 10 inches. If you think these values are too high, you are probably right, modern scholars assume that these values are probably idealized.

Strength, Stamina, Agility and Eyesight

Other important physical attributes were of course strength, good posture, stamina, agility and eyesight. There is one known example of a soldier being dismissed due to weak eyesight.


Finally, the maximum age for joining was around 35 years, whereas the minimum age was about 13 years. But these are extreme examples, most recruits joined between the ages of 18 and 23 years. Note that the service period lasted for 16 to 30 years depending on the branch of the Army.

Mental Requirements

Next are the mental requirements, these were probably of lesser importance, but legally it was allowed to discharge a soldier based on physical or mental defects.
Education was probably not a major requirement for the common soldiers, but since commands were given in Latin a recruit had to have a sufficient understanding of it.
Furthermore, since the Army needed specialist a good education probably could tip the balance. For instance specialist posts like the signifier, who were in charge of the accounts and funds, required well educated people with good legal records, which brings us to the next point the legal requirements.

Legal Requirements

Slaves, former slaves – the so called “freedmen” were not allowed to join the Army, only in dire situation were they conscripted. Only freeborn men were allowed in the Roman Army and to join the Legionary Units the recruit also needed the Roman Citizenship.
There were other legal requirements too, we can assume that most crimes would prevent joining the Roman Army. Trajan ruled that convicts of capital offenses, adultery or any other major crimes were not allowed to serve.

Note that modern scholars have different views on how thorough or superficial these legal examination were performed.
Finally, there are some examples that a recruits used letters of recommendations in order to provide references for their “good character”, this is also a debated topic, since only a few of those letters are known.

Probatus (approved)

But even after passing these requirements the recruit wasn’t a full soldier yet, he was now considered “probatus”, which meant he was approved for training in which he needed to pass several proficiency tests. Note that in this period the punishment for failing in discipline or even criminal acts like selling military equipment was less severe and even pardoned.

Signatus (“enlisted”)

After the recruit trained for at least 4 months and passing all proficiency tests, he was “signatus”, thus he became fully enlisted. The name of the recruit with his age and any distinguishing marks would be added to the unit’s record. Now he was considered a full soldier and the recruitment process was over.


Although not all information is undisputed it is clear that the Roman recruiting process was systematic and well organized in order to ensure a constant flow of high-quality recruits to keep the ranks filled. Nevertheless, these new troops also needed further training, which will be topic of another video.
Thank you for watching and see next time!

Related Articles

Imperial Roman Army – Organization & Structure
Imperial Roman Army – Training




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Online Resources

The Military Institutions of the Romans (De Re Militari) By Flavius Vegetius Renatus-Translated from the Latin by Lieutenant John Clarke

Ancient Roman units of measurement