Addendum: The Size of the Late Roman state.

Here I explore a related aspect of Brown’s account that appears problematic: his claims about the size of the late Roman state.

Brown claims that the post-Diocletian Roman state was a “command economy” capable of mobilizing tremendous resources and driving the Roman economy. I am skeptical of such a description being an accurate description of a premodern state. Prior to the railway and telegraph, there were severe limits to ability of states to direct economic activity. To get a feel for things I tried a back of the envelope calculation of the size of late Roman fiscal military state.

The main component of the Roman state was the army. The army grew considerably after Diocletian’s reforms. The exact size of the new army is subject to considerable controversy. John Lydos estimated the Roman army to comprise 389,704 men and a navy of 45,562. The largest estimates are based on Agathias and date from the mid-sixth century. These suggest that the total size of army and navy was around 645,000 (580,000 in the army and around 65,000 in the navy). Historians tend to think these number are too high but we will accept them for the purpose of the argument (Agathias is critiquing the government of his day by showing that the army had declined greatly from the days of Diocletian).

Unfortunately estimates of the Roman population are extremely rough and we don’t have any good numbers of the 3rd century. The population of the Roman empire c. 160 is estimated to have been between 60–70 million. The population in 300 was likely lower than this, though it is unlikely that it was substantially smaller, as recent research suggests that the economic vitality of the empire did not collapse as rapidly in the 3rd century as was once thought.

If we take the largest estimate of the size of the Roman army and take a pessimistic view of Roman population in 300 estimating it to be 50 million (noting that is a pure guesstimate and not based on any definite evidence), we obtain an estimate that the Roman army made up 1.3% of the population. If we employ John Lydos’s numbers we obtain an estimate of 0.87% of the population.

These numbers do not suggest that the Roman army was especially large or burdensome in comparison to other advanced preindustrial societies. In the late seventeenth century, the armies of Louis XIV represented as much as 2% of the French population of 20 million. The Dutch Republic in the 1750s also employed 2% of its population in its armed forces (45,000 out of a population of 2.25 million). The Prussian state employed around 3.5% of its population in the army in the mid-eighteenth centuries. Even Britain employed around 1.2% of its population in its army as perhaps as much as 3.8% of its population in the navy at the height of the Napoleonic wars (approximately 400,000 out of a population of 10.5 million).

What about the size of the Roman bureaucracy? It is accepted that the bureaucracy of the principate was tiny (perhaps 10,000 individuals, many of them freemen and slaves of the imperial household). The late Roman bureaucracy was substantially larger. But even if the bureaucracy after Diocletian was ten or fifteen times larger than that of the Augustinian empire, it would not meaningfully change our comparisons. At most around 1.6 % of the population would have been state employees (either soldiers or bureaucrats).

These numbers are not trivial. They certainly attest to the tax-raising powers of the Roman state. The successor states would not be able to maintain professional armies or bureaucrats at all. Nevertheless, it seems implausible to describe a state that employed less than 2% of the population as a “command economy”.