The Number Problem in the Persian Wars 480-479 BCE

Quite a few people interested in ancient warfare know an article by one F. Maurice on the water and roads at the Hellespont. After reading Herodotus’ story that Xerxes marched through the area with 1,700,000 infantry, 80,000 cavalry, and 20,000 charioteers and camel-riders and hiking around the countryside in summer, he argues that an army of 150,000 soldiers, 60,000 noncombatants, and 75,000 animals is the absolute maximum that could have been fed and watered in the area (paragraphs 10, 21, 33). I think this was the Major-General Sir Frederick Barton Maurice who was forced out of the British Army for political reasons in 1918, became a journalist and an advocate for veterans, and died on 1 May 1951. People cite it because he was an experienced staff officer who had walked the ground and talked to classicists like J.A.R. Munro. Its full of details such as that the British Expeditionary Force of 72,000 men, with railroads for supply but just horses for transport, needed 20 square miles for its camp in 1914 (the cavalry were stationed elsewhere and the motor vehicles had not yet arrived). But its certainly not the last say, and while he was talking to British classicists, a retired Bavarian general was preparing a study of the same problem and addressing their arguments.

One Robert von Fischer (d. 1937) commanded the 1st Royal Bavarian Landwehr Division in France from September 1914 to December 1915 and received the honorary title of Bavarian General of Infantry in 1917. He had similar military credentials as Maurice: he commanded a division on the Western Front for 16 months, Maurice served in the Tirah Expedition in Afghanistan, the Boer War, and briefly on the Western Front. And after examining the whole route and the problems involved, he felt that the Persian army was probably no more than 40,000 soldiers strong.

One fundamental problem is that for long stretches of the route, the Persians were forced to take a single road, such as their march along the Gallipoli Penninsula between the sea and steep hills. And if that is really a single road, with no grass at the side for the troops to march along while the baggage train follows the road, then an army of 10,000 infantry, 2,000 cavalry, and 700 two-horse carts will occupy at least 21 km of road. That is pretty close to a day’s march, so in his day the rule of thumb was to send ideally no more than one division (15,000 heads), if necessary an army corps (45,000 heads), and if there was no alternative two corps (90,000 heads) down a single road (pp. 298-299). When the head of that two-corps column halted, it would have to wait up to four days for the rest of the column to catch up. This way of “marching divided but fighting united” first became common in the Napoleonic Wars with the introduction of professional staffs trained to prepare maps and timetables and keep the different parts of an army in communication with one another (the Mongols in the 13th century also managed it). It is not what Herodotus describes. And so von Fischer pointed out the problem with saying “If Napoleon could invade Russia with several hundred thousand men, why couldn’t Xerxes invade Greece?”

According to Herodotus a land army of 1,700,000 infantry, 80,000 horsemen with a baggage train (Troß) of at least the same headcount- so twice the headcount as the German army employed against France in 1914- was supposedly gathered by the Persian king Xerxes in Asia Minor in 481 BC. The individual contingents from the most distant parts of the empire already had up to 4,000 km behind them when they arrived and had to march for more than half a year. And this mighty army was then in the spring of 480 lead 1,200 km further from there across the Hellespont through Thrace and Thessaly before they finally confronted the enemy. The length of the march column of this army with baggage train, marching along a single street, must have amounted to at least 4,000 km (the great circle distance from Lisbon to Moscow) and the march from the rear of the column to the front must have required seven months’ time! Was there in Xerxes’ army a logistical wizard, who could feed such masses without railroads; was there a Moses, who could supply such gigantic masses of humanity and animals with water? Or did the Persian have aircraft and wireless telegraphs for the transmission of messages, commands and miscellaneous communications of the commanders across thousands of kilometers? If the great general Napoleon lead only 450,000 men into Russia in 1812, well-organized, disciplined, exercised troops with professionalized, experienced officers and staffs, and certainly not on a single street, but along many roads over a breadth of several hundred kilometers, nevertheless his plans shattered on the very same distances and difficulties of supply!
…
Indeed armies of 200,000-300,000 men operated in Germany, Austria, and France without modern means of transportation in the time of Napoleon I. But these were the well organized, disciplined, well trained troops under professional leadership, and, what should be especially emphasized, they marched in separated march columns of moderate strength through intensely cultivated, wealthy districts cut with numerous streets, in which they could live to a good part from the produce of the land, and therefore also, aside from greater frugality, could satisfy themselves with a much smaller baggage train (Troß), while a union of larger bodies of troops for the battle took only a few days.

Its true that Herodotus says (9.28) that the free Greeks eventually gathered an army of almost 40,000 hoplites to face the Persians at Plataia. But that was after the Persians had already suffered some setbacks, and when they were planning their invasion the King’s Men were probably expecting to fight a coalition of a few cities the size of Sparta and Athens, with 6,000 to 10,000 hoplites each, plus a handful of smaller cities with a thousand or two hoplites each. Thucydides insists that the battle of Mantinea, with about 10,000 hoplites on each side, was the greatest battle between Greeks “for a long time” (5.74.1). An army of 40,000 or so soldiers, minus losses and plus local allies like the Thessalians and Thebans, should have been enough for people who hadn’t read Herodotus and learned that one Greek was worth three barbarians.

At the end of his article von Fischer turns to the problem of how Herodotus could repeat such an absurd idea:

Contemporaries of the events also lacked the understanding and above all a measure for estimating troop strengths. People who had never yet seen large bodies of troops in different formations overestimated correspondingly their numbers very significantly, especially in the case of long march columns with baggage train (Troß). In times of excitement such overestimates multiplied. So one can assume that from the beginning such excessive numbers spread from mouth to mouth in Greece, were further increased and confused in the excitement of wartime and probably also for the increase of the fame of their fellow-countrymen, until they finally arrived over the whole generation between the war and the investigations of Herodotus, who in addition was more than uncritical about measures and numbers and had no precise understanding of military matters.

After all, the largest battles we hear about in archaic Greece involve a few thousand hoplites on each side, and its likely that the typical Greek battle before the Persian wars took place when an aristocrat lead a few hundred friends and hangers-on up a beach or over the hills to steal some cattle and slaves and tripods. And von Fischer could have mentioned that Xenophon and Thucydides and Diodorus describe how easy it was to overestimate the size of an army which marched slowly two abreast, made more shelters or campfires than expected, or whose market mob was unable to get away before the fighting and took shelter behind the soldiers screaming and throwing things. His rule of thumb of no more than 45,000 heads along a single road is pretty close to figures for large but not gigantic Macedonian and Roman armies which seem to have all come into the same camp in a single night.

Without Persian documents, we can’t know the size of the army that invaded Greece in 480. But its important to remember that the idea that the invasion of Greece was an overwhelmingly important event, or that eastern armies were especially large, is only found in classical literary sources. No Babylonian or Assyrian king claims to lead more than 120,000 men (and I don’t know anyone who thinks that that number is based on a count). And in all of world history, I can’t find solid evidence for an army of 100,000 120,000 or more men before the Napoleonic Wars. And while an invasion of tens of thousands of soldiers from beyond the sea was the biggest thing which had ever happened in Attica, for the Persians it was Tuesday. Everyone from Aristophanes to Thucydides to Theopompus said that the Athenians loved to talk up what they had done against the Persians, and there are people today who think that the Spartan reputation as tough guys was born at Thermopylae.

As a general rule, British critics tend to try to save as much of Herodotus as they can, while Germans and Austrians are franker that he or his sources could just have made things up. Where British commentators often rely on common sense and look very closely at ancient texts, Germans apply reason and general principles. So I think that its characteristic that where Maurice calculated the largest force which he could imagine leading through the area, von Fischer thought about it and gave the size of army which would be most practical.

I thank Ursula Weber for citing this article in Das Reich der Achaimeniden: Eine Bibliografie (1996).

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Further Reading:

• Maurice, F. (Frederick Barton) (1930) “The Size of the Army of Xerxes in the Invasion of Greece, 480 B.C.” Journal of Hellenic Studies 50 pp. 210-235
• von Fischer, Robert (1932) “Das Zahlenproblem im Perserkriege 480-479 v. Chr.” Klio 25 = N.F. 7 pp. 289-333 link
• Lee, John W. I. (2008) A Greek Army on the March: Soldiers and Survival in Xenophon’s Anabasis (Cambridge University Press: Cambridge)
• Roth, Jonathan P. (2012) The Logistics of the Roman Army at War (264 BC – AD 235). Brill: Leiden.

Edit 2022-03-01: fixed formatting broken when WordPress introduced the block editor