Late Roman Unit Sizes

[Nathan Ross]

comparing to the fortresses of late period, more similar to middleage castle.

That was what I'd thought - but if you look at that ground plan of Lejjun, the internal space doesn't look to be used all that economically. In fact, Principiate fortresses like Novaesium or Inchtuthil look far more densely occupied. Troesmis is very dense, but only a few of the internal buildings are barracks.

Granted, the plan above probably shows the situation in the 6th century, after an earthquake c.500 I think and a partial rebuilding of some areas of the fort. But the barrack sizes and spacings are, I think, original. Even if there were originally large barracks in Areas O and M we'd still only have 20 blocks, enough for 1200-1600 men. That gives a very similar 'men per hectare' ratio to the 1st-2nd century fortress at Caerleon (approx 300 men per hectare).

There's also a possibility that parts of the legion were out-stationed. Khirbet el-Fityan fort, at 0.6 hectares, is the same size at Axiopolis near Troesmis and might have played a similar role in housing a reduced-size cohort.

But I don't think we can assume any more (as several historians once did) that a limitanei legion was substantially larger than a legion of the comitatensis - 3000 men or so. Instead, they might well have been exactly the same size - 1200 or so at full strength.

How would this alter the various calculations for troop numbers in the ND? If frontier legions were 1200 men, and frontier cohorts and milites units were between about 60 and 240 men, we'd have to adjust our estimates downwards.