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Relative size of the Roman army

PostPosted: Fri Aug 19, 2005 12:06 pm
by Quintus Pomponius Atticus
Salvete omnes,

Reading Susan P. Mattern's "Rome and the Enemy", I was surprised at reading that "It has often been remarked that under the Principate, Rome managed to secure, defend and even expand is empire with a relatively small military force". (p. 82). The author argues that "This small, fixed size of the army...was a key factor in Roman strategy" (p. 83).

She estimates the size of the Roman forces at about 400.000 men (p. 83). Not exactly a small army, I'd say, if we compare this to the relative military strength of modern nations.

It is generally accepted that, under the Principate, the Roman Empire had about 60 to 80 million inhabitants. If we take 70 million as a good estimate for our calculations, this would mean that app. 1 out of 175 Romans were active in military service.

Now, let us compare these figures with those of a few significant modern military powers.

The United States have an active military force of 471.500, out of a population of 295.734.134; that is 1 American out of 627 serving in the army.

The United Kingdom has an active military force of 113.900, out of a population of 60.441.457; that is 1 out of 531 citizens.

Russia has an active military force of 350.000, out of a population of 143.420.309; that is out out of 410 Russians.

If we take the average of these figures, I arrive at the result that the relative military strength of the Roman Empire was three times that of the modern nations mentioned here.

Two comments should be made upon this result, one relativizing the strength of the Roman army, the other making it look even more impressive.

The first comment is that a modern army, due to its uncomparable technological equipment, needs far less manpower to be effective; weaker numbers thus do not mean less performative armies.

A second consideration is that modern nations can command the resources of strongly developed industrial economies (with a much more extensive and weighty taxation system), much more productive and sizeable than Rome's relatively primitive, largely agrarian economy; this means that for Rome, the cost of maintaining such a large army was an uncomparably greater challenge.

Any comments about or corrections on my figures and conclusions ?

Valete,

Atticus

PostPosted: Fri Aug 19, 2005 3:53 pm
by Primus Aurelius Timavus
One consideration is that modern countries rely on reserves and civilian support that were virtually unknown during the principate. In the case of the US, here is a quote from Secretary of Defense Donald Rumsfield (well beloved in Old Europe, I understand) that quantifies this in the case off the US:

...With a million-four men and women in the armed forces and an number of reserves on active duty, and six or eight hundred thousand civilian employees, you've got an organization spread all across the world of over 2-and-a-half-million people. At any given moment of the day or night, some one of them is doing something wrong. (Laughter.)


Using the figure of 2.5M involved in military operations or supporting them, we arrive at a figure of 1 American in 118 in the military. (Note that this calculation includes only reserve forces that have been called to active duty, and not those merely training one weekend a month plus two weeks in the summer.)

This proportion is greater than that of Romans under arms.

More broadly, I question Mattern's estimate of 400,000 in Rome's army. That sounds high to me. Perhaps it is a maximum figure rather than the average figure?

Tergestus

PostPosted: Fri Aug 19, 2005 4:29 pm
by Quintus Pomponius Atticus
Salve Tergeste,

Thanks for mentioning additional figures. In fact, I used only the number of "Active Military Personnel", based on statistics published at http://www.globalfirepower.com/united_states.asp

As for Mattern's figures, they are based on the work of Birley (1981) and Holder (1980). Here is how she arrives at app. 400.000 for the principate :

"As for auxiliary units, it was Tacitus' impression that they were approximately equal in strength to the legions (Ann. 4.5). In fact, under Antoninus Pius, one scholar counts more than that : 338 quingenary cohort, each about 500 strong on paper; and 48 milliary cohorts, numbering twice that, with an estimated paper strength of about 224.000. Whether the auxiliary units were also underenrolled is more difficult to say. There seems to have been some flexibility regarding the size of these units, and some contained more soldiers than they were supposed to, others less. The legions at that time number twenty-eight, for a paper strength of about 140.000 or 168.000, depending on the size of a legion; adding the praetorians and other troops stationed in Rome, plus perhaps 30.000 for the fleet, this amounts to a paper strength of 405.000 or 433.500 for the entire army. We should probably allow for underenrolled units, imagining an actual figure of, perhaps, 400.000." (p. 82-83)

Vale,

Atticus

PostPosted: Sat Sep 03, 2005 10:45 pm
by Gnaeus Dionysius Draco
Salve Attice,

Another question, one we've talked about already: how does one calculate the amount of people in the Roman Empire? I guess Roman citizenship was pretty well documented at the time, but how about slaves, mercenaries, merchants or illegal immigrants? Also, I would think many of the revelant documents were lost over the centuries.

Vale,
Draco

PostPosted: Sun Sep 04, 2005 9:42 am
by Quintus Pomponius Atticus
Gnæus Dionysius Draco wrote:Salve Attice,

Another question, one we've talked about already: how does one calculate the amount of people in the Roman Empire? I guess Roman citizenship was pretty well documented at the time, but how about slaves, mercenaries, merchants or illegal immigrants? Also, I would think many of the revelant documents were lost over the centuries.

Vale,
Draco


Salve Draco,

I will look things up in a recent book I found on the subject a.s.a.p. :

Walter Scheidel (ed.), Debating Roman Demography. Mnemosyne Supplement 211. Leiden: Brill, 2001.

Vale,

Atticus

PostPosted: Thu Sep 08, 2005 10:18 am
by Quintus Pomponius Atticus
Gnæus Dionysius Draco wrote:Salve Attice,

Another question, one we've talked about already: how does one calculate the amount of people in the Roman Empire? I guess Roman citizenship was pretty well documented at the time, but how about slaves, mercenaries, merchants or illegal immigrants? Also, I would think many of the revelant documents were lost over the centuries.

Vale,
Draco


I asked a professor who teaches Roman demography and he called the numbers given for the population of the Imperium Romanum 'guesstimates'. Although most scholars agree that we should look between 50 and 80 million inhabitants (which is a rather wide margin !), the extremes run from 30 million to over a 100 million.

The numbers are calculated based on - highly uncertain - numbers in ancient texts, guesses of the total population of a region based on - highly uncertain - partial numbers in ancient texts, estimates based on the surface of farmland available in a region, estimates reckoning with the urbanisation of an area etc. etc. Many elements are inferred in the calculations that need to be accepted on faith, rather than on proof.

This uncertainty is one of the reasons why the study of demography in the ancient world has focused on different themes (life expectancy, gender demography etc.) for the past 15 years or so, mainly through the influence of W. Scheidel (Stanford Univ.).

Vale,

Atticus

PostPosted: Sat Sep 17, 2005 1:15 pm
by Gnaeus Dionysius Draco
Salve Attice,

Given this some more thought, and come up with something very simplistic. If we know the amount of people now living in Europe and its surrounding regions, can't we simply trace back to previous ages? I would think we know the average amount of children per capita for the last 200 years or so (or even more), so reasoning back from there, can't we arrive at a reliable number? The only things I would think disturb such a calculation are great wars and diseases, but even though war is a terrible thing, it rarely exterminates an entire population or even half of it.

Vale,
Draco