A domus on the Esquiline, Rome, January 163
Quintus Ptolemaius Eupater was drinking wine with his father. He was the third son of the family and thus not active in the family business, having been sent instead into the imperial administration where he worked as the supervisor of an office in charge of statistics. He was often sent on long fact finding missions around the Empire and had come back from one such mission only two months before, but it was the first time he really had the opportunity to spend time with his family.
After answering one of his father's’ question he remarked offhandedly : “You know that we missed a lot of money when we did not invest in horseflesh?”
“How so ?” asked his elder, raising an eyebrow. “Well, you know that since the conquests of the divine Hadrian the army has expanded to add more than ten thousand horsemen to its rolls ? All those horses have to come from somewhere, and you know that the rise in fame of senatorial families such as the Flavii Arianii is directly linked to their rôle in providing those beasts... “
“How do you recon such things ?” asked his father, now interested in the topic. “As you know father, the army has thirty legions, some 165 000 infantrymen alongside some 4000 legionary cavalry. This has not changed since the time of the Optimus Princeps the divine Trajanus and is not even that far from the twenty eight legions on record in the time of the divine Augustus. But while the citizen soldiership has not been expended it is another story for the auxiliary units ! In fact many of the units now fighting the Persians in the East did not exist thirty years ago... “
His father scratched his beard while his son took a sip of wine before he said : “But there are not that many more senators serving in the army, and the Senate has not been expended… So the army can’t have grown that much, can it ?”
His son smiled : “Good observation father ! And quite true too. But it’s because the expansion has been made not so much with new units as with transformation to existing units. I’m not sure how many auxiliary units existed at the time of the divine Trajanus, but it must have been around 380. Now the list I’ve just compiled for the Academia Militaria records four hundred units and some 270 000 men taking their pay from the Emperor, so just twenty more units, around ten to fifteen thousand men with about half being cavalry alae or cohors equitata. But what I’ve seen is that many units that were only cohors quingenaria or miliaria have received new detachments of horsemen, from 120 to 240 depending on whether it was a larger or smaller unit. It did not change the requirement for higher officer of senatorial rank but if course the number of more junior officers has increased, with a number of junior sons from equestrian families such as myself entering the military career, especially those from the more provincial families who hope to improve their connections in Rome. There have been more promotions for soldiers from the ranks too.”
“You know that it is, in and of itself, another opportunity we have not identified… More centurions and decurions means more men who will retire to their provincial plots of land with money which they can spend however they want, drinking it of investing it… In any cases peoples with money to buy things we could sell them... “
“Oh I don’t think so, they don’t really regroup to provide markets, they are too far apart from each other, although they may help develop small villages and other kind of rural areas by improving inns, relay posts, taverns and those sort of places in which many veterans seems to invest…”
“Still, from what you’ve said the army is only as big as about half the population of the city of Rome… That seems so small for an Empire of the size of the Rome…”
“It depend how you look at it father. Those 400 000 men cost about 200 000 000 denarii a year, about 500 denarii per soldier. Of course the rank and file only cost half of that, but officers, horses and the rest of the equipment cost a hundred millions denarii a year. That’s a lot of the empire’s income…”