The command structure of the Roman legion operated with this really beautiful hybrid
of a top down and a bottom up system.
The smallest unit in a legion was the contubernium.
This was a group of 8 men.
These men ate together, marched together, slept together, (not like that), and took
care of one shared pack animal together.
One of our sources writes about a military tradition where men paired off with another
member of their contubernium.
These men would watch each other's backs during battle, go on guard duty together, and if
one of them were killed the other would contact their families and hold a funeral service.
This was in effect the smallest unit in the Roman army, but it was so informal that we
don't even have a name for it.
The man in charge of the contubernium was called the Decanus.
Decanus, Dec, leading eight men, why not Octanus?
Well a contubernium actually had two hidden members.
Servants, or maybe slaves, to help with taking care of the pack animal, patching up equipment,
cooking, cleaning, things like that.
So in some instances, like this one, they were counted, but they were non combatants,
and unimportant for our purposes.
Going forward *we* will not count them.
So a Decanus lead a unit of eight men, which is part of this bottom up system.
Not a lot of information survives about the Decanus, but we know that they were selected
from the contubernium, by the contubernium.
In other words this wasn't a promotion by an officer, but rather an election by their
peers.
In practice, the Decanus tended to be the most experienced man in the contubernium.
He helped keep order while on the march, and disciplined his men when they got out of line,
but in battle he had no significant tactical role.
We need a bigger units for that.
A century was a group of 80 men, and was the most basic tactical unit that the Romans used
during battle.
Century, 80 men, again, it doesn't make sense.
Remember how the contubernium had 8 soldiers and two, let's call them helpers?
Well that naming inconsistency carries forward.
A century consisted of ten contubernia, meaning there were 80 soldiers and 20 "helpers" total.
A century was the smallest organizational unit that fought as one.
Each had their own standard, their own traditions, and soldiers would openly joke about how certain
centuries were better than others.
A century was commanded by a centurion.
There sere 59 centurions per legion, and these were the career officers of the Roman army.
This position was very much top down, because centurions were promoted directly by their
superiors, and once promoted, they held life or death power over the men in their century.
Every centurion had an optio, or second in command.
These men were in charge of the training and discipline of the century, and could take
over for the centurion if it became necessary.
In battle, the centurion lead the century at the front, which was actually quite dangerous,
while the optio stayed at the back in the opposite corner of the formation.
This was so the centurion could, you know, lead, while the optio made sure the formation
was solid and that nobody ran away during battle.
Cohorts consisted of 6 centuries, making them 480 men strong.
There were ten cohorts in every legion.
If generals were moving men around during a battlefield, they were moving cohorts.
Each one had it's own unique trumpet call, so they could receive orders at a moments
notice without the use of messengers.
Here's another bottom up system, and this one's really interesting.
There was no dedicated commander of a cohort, but there was an institutionalized command
structure.
Of the 6 centurions in the cohort, the most experienced centurion would automatically
assume command of the entire unit, while the other five would fall into subordinate positions,
and act as advisors to the lead centurion.
To be clear, every centurion still commanded their own separate century, it's just that
the lead centurion also issued orders to the rest of the cohort.
If a lead centurion was transferred or went into retirement or was killed, the roles would
automatically shift around and the next most experienced man would get the job.
It's this really unusual system where cohorts were incredibly important to the legion, but
command had nothing to do with how they governed themselves.
Now, everything I said before about cohorts is true, except none of it applies to the
first cohort in every legion.
The first cohort was always it's own unique thing.
They consisted of 5 special double strength centuries.
The cohort itself wasn't double size, but it had five double strength centuries instead
of the normal six.
This meant that the first cohort would have 800 men, making it 60% larger than cohorts
2 through 10.
Since every centurion in this cohort commanded 160 men rather than 80, they were seen as
special.
They outranked normal centurions from every other cohort.
Transfer into and out of the first cohort was a command-level decision, which means
that the first cohort, unlike all of the other ones, was, to an extent, controlled by the
higher ups.
Belonging to the first cohort was extremely prestigious, even if you were a low level
grunt.
The first cohort hosted the legion's eagle standard, and, in theory, protected the commander
of the legion, which I'll get to in a minute.
The person in charge of the first cohort was the most experienced of these 5 super-centurions,
and was called the Primus Pilus.
He was the highest ranking front line soldier in the entire legion.
He would sometimes be called up by the commander of the legion to give his advice, and to devise
strategy.
In this way he was responsible for representing the views of the rank and file centurions
to the higher ups.
If the men had a problem they would go to their centurion, who would go to the Primus
Pilus, who would go to the commander of the legion.
There's that bottom up system again.
There are isolated incidents where the Primus Pilus would actually take command of the entire
legion, which just shows how much authority they had over their fellow centurions.
Unofficially, this made them the forth in command of the legion.
The official third in command was someone called the camp prefect.
They were basically a quartermaster, in charge of supplies, food, and the construction of
the fortified encampment that legions liked to build.
A pretty mundane job, except that this man was also a former Primus Pilus, meaning that
he had decades of experience under his belt, and experience leading the supersized 1st
cohort.
This was the highest rank available to a career soldier.
It never says this explicitly in our sources, but we get the impression that this was a
cushy job away from the front lines, well suited for a Primus Pilus past their prime.
But I don't want to detract from this position.
They were appointed by the commander of the legion, top down, but once in place they were
the very embodiment of the institutional memory of the legion, bottom up.
Commanders would come and go, but the old camp prefect would stay put until retirement.
The second in command was someone called a military tribune.
Get ready, because this one's a little complicated.
The Military Tribune was an elected position.
It was seen as an early step in a political career, normally taken by young men before
they could officially enter the senate around the age of 30.
This meant that military tribunes tended to be sons of senators, or sons of wealthy families
aspiring to have their first senator.
Aristocratic, but with an eye towards pleasing the voters back home.
Top down, and bottom up.
In the old days there were 6 equal military tribunes, and they would take turns commanding
the legion, as a form of training.
When the army became more professional, this system was done away with.
They replaced it with this.
Five of the six Military Tribunes were called Thin Striped Tribunes, after their clothing.
These young men were basically personal secretaries to the commander of the legion, and had no
real responsibilities.
Their only role was to watch and learn.
They had no command authority, no combat ability, and no responsibilities during a battle.
They were a bit of a joke, even in their own time.
We can safely ignore the thin striped tribunes.
They're dead to us.
One of the six Military Tribunes was called the Thick Striped Tribune, and these are the
important ones.
They tended to be the sons of respected senators, and were separately elected, with actual responsibilities.
They were the second in command of the legion, and had the authority to lead men into battle
if necessary.
They were still young men, inexperienced, but highly respected, unlike their thin striped
counterparts.
A broad striped military tribune could reasonably expect to go on to become a senator.
Finally, we have the commander of the legion, the legate.
This was a senator, appointed by the senate to command a specific legion for a specific
length of time.
Very top down.
In all, legions consisted of 5248 men, including 128 cavalry, 640 Decani, 59 Optios, 59 Centurions
of various rank including the Primus Pilus, 1 Camp Prefect, 1 Military Tribune (that matters),
and 1 Legate.
What's really interesting is that the three command positions within the legion, the camp
prefect, the military tribune, and the legate, represent these three different sources of
power.
The camp prefect represents the professional soldier, from the bottom up.
The legate represents the will of the senate, from the top down.
And the military tribune represents the aristocracy and the people back in Rome, which is a complicated
blend of the two.
The balancing act that they're trying to pull off here is a really different way of thinking
about bureaucracy.
One man was appointed, one was elected, one got there through seniority, and all had very
different constituencies to please.
But by using this system the legion as a functional unit remained dynamic for centuries.