Late Roman Legion size based on the Perge Inscription

[FlaviusB]

I find Jonathan Ross guilty of doing exactly the same, loose with the numbers. Like many academics, anything that jeopardises his theory is dismissed. For example, Suetonius gives a legion at 5,600 men, and because this does not sit well with his theory of a legion having 4,800 infantry and 1,200 slaves, he writes “Suetonius is almost certainly referring to a republican legion consisting of 5,200 infantry and 400 cavalry.”

So, Roth, prove it. Give me a troop breakdown of the 5,200 infantry plus their organisation, and the same goes for the cavalry. 5,200 infantry divided by 60 centuries per legion equals 86 point 66. So how does that work? And exactly how are the 400-cavalry organised? Give us details. Surprising to many, Tacitus, Josephus and other support Suetonius’ 5,600 figure. I am seriously convinced that academics must be the most mathematically challenged people on this planet.

Roth explains that Lydus assigns 6,000 men to a legion and Lydus gives the date for this legion to the early republic. Roth throws in the usual put down that “Lydus’ numbers are not dependable.” Again, Roth makes no effort to try and understand Lydus. Roth tells us that Lydus gives the date of the 6,000 legion to the early republic. Actually, Lydus gives the year as being 388 BC. Now anyone who knows their Roman history, will be aware that in 387 BC, the Romans added four new tribes, bringing the total to 25 tribes. Has anyone study whether there is a connection? Answer…no.

Let me share some of my research. Lydus, writing in the fourth century AD, has interpreted the 60-centuries as having 100 men, so the legion blows out to 6,000 men. Lydus is not the only ancient historian who has confused a century as having 100 men. There are a few more examples. Take Servius for example, he claims a legion had 6,000 infantry and 300 cavalry. Servius has the right cavalry numbers, but like Lydus has multiplied the 60 centuries in a legion by 100 men.

In relation to Hyginus, Roth writes: “If all personnel in a legion were assigned to the ranks of the centuries, regardless of their status, then the total number of soldiers authorized for a standard imperial legion would be exactly 4,800. Accepting this hypothesis, however, leaves unresolved the question of Pseudo-Hyginus' "missing" 1,200 men. They can be found by carefully noting Pseudo-Hyginus' terminology: he gives the number of "soldiers" (milites) in a century as 80, but says that the cohort has 600 "men" (homines). Indeed, there is a military category which belonged to the legion, but would be homines and not milites: non-combatant slaves. It is confusion about the role and number of military slaves which has led to both ancient and modern perplexity over the legion's size.”

And this is the crutch of Roth’s problem. Roth believes the discrepancy between a legion of 4,800 and 6,000 is due to 1,200 slaves being added to the legion. I can see why many have rejected his theory. It is baseless and preposterous. Like the example I earlier provided in the Vegetius posting above, Roth has no idea of how the legion was organised when in camp, and Hyginus is explaining the Roman army when in a camp. It’s the camp layout. Taking Roth’s 4,800 infantry for a legion, which would be organised into 10 cohorts each of 480 infantry, and following the camp doctrine for the principate, two cohorts amounting to 960 infantry are distributed amongst the remaining eight cohorts, so, 960 infantry divided by eight cohorts equals 120 infantry. Therefore, each of the remaining eight cohorts increased from 480 infantry to 600 infantry as per Hyginus. Someone, tell me where the maths is wrong.

The Suetonius quote comes from a fragmentary source, but the 5200-5600 figure aligns with Polybius' and Livy's statements that Republican Legions between the 3rd and 2nd centuries BC rose from 4-4200 to 52-5600, and that the Legions varied in size based on available manpower and campaign demands. Roth cites Kubitschek's entry on the Republican Legions from the Pauly-Wissowa, Real-Encycloptidie der klassischen Altertumswissenschaf as his source in this instance. 

Since the Legions at this time comprised 4 different classes of troops (Velites, Hastati, Principes and Triarii), it makes no sense to try to apply their figures numbers one-to-one to the Legions of the Late Republic onwards, when we know that those four classes no longer existed by that point. As to your suggestion that Tacitus supports the 5600-man Legion, Roth cites Tacitus' account of a mutiny in AD 14 where a Primus Pilus received 60 lashes for every century in the Legion; your math on 5200/60 is correct, and 5600/60 doesn't work either. 

388 BC is the Early Republic and is a year before 387, so there's no way that adding 4 new tribes the year after could account for a Legion having 6000 infantry and 600 cavalry the year before. Considering his numbers far exceed those of Polybius and Livy which Roth also cites, and who were writing much closer to 388 BC than Lydus was, I would say this makes his numbers unreliable. As for Principate doctrine parcelling out two cohorts among the other camps, this contradicts Hyginus' own statement (per DB Campbell's article "The Problem of the First Cohort), "the first cohort [...] will receive a double plot, seeing that it has double strength." Why partcel out two cohorts among the others when you've made accommodations for the double-strength first cohort to encamp with all of it's men together?