Ancient army numbers

[Nathan Ross]

How large were the largest Roman expeditionary armies?

Roman army numbers are also, I believe, commonly inflated. I've argued here, for example, that the figures of hundreds of thousands of men suggested for Trajan's Dacian campaigns are probably mistaken - the actual total for the force was more likely 50-60,000.

Lee (War in Late Antiquity) notes that 4th century campaign armies were comparatively small; 15-30,000 is typical. One of the largest appears to be Julian's Persian invasion force, of around 65,000 men. Trajan's Parthian expedition probably had very similar numbers.

A few Roman-related figures on the supply problem:

Goldsworthy (Roman Army at War) estimates that a single legion of c.5500 men would consume 100 bushels of corn a day: the equivilant of 70 acres agricultural production a week*. A legion also ate 12 oxen, 120 sheep or 38 pigs per day, and required nearly 1000 baggage mules (who also needed fodder, of course)

* I think he gets this figure from Piggot, Roman and Native in North Britain; but Piggot gives the figure as 20 acres!

Lee (again, as above) estimates that an army of 10,000 men required 23.5 tons of food per day, including fodder for 4000 cavalry with 1000 remounts. hock:

Muliplying these rough figures gives some idea of the astronomical demands that a large army would place on food production and supply. Keeping tens of thousands of men in a cohesive group in the field would strip whole areas - an army of 100,000 or more would leave entire provinces denuded of food, with famine in its wake; the logistical problems of collecting the food and delivering it as a daily ration would be immense, and half the army would probably be starving before they even reached the battlefield!

Going back to the Greek v Persian issue - might it be possible that the irrigated farmlands of, say, Mesopotamia would have been far better for supporting large armies than the less cultivated lands of Greece? The Persians may have been able to field an army hundreds of thousands strong on their own territory, but would they take such a force on expedition into country less capable of supporting them?

:-?