Every medieval historian, whatever his race, invariably indulges in wild and picturesque exaggeration whenever he has to estimate numbers that cannot easily be counted. It is therefore impossible for us today to establish the actual size of the Crusading armies.I came across this bold assertion a few weeks ago in Steven Runciman's History of the Crusades. It reminded me of many similar statements that I had read in the past, all of them calling into question the ability of ancient and medieval people to count in large numbers.
One prime example of this is Herodotus' count of Xerxes' invasion army which he places at 2.5 million men. Always eager to "show his work," Herodotus explains that Xerxes derived this number by counting off ten thousand men, herding them into a tight group, and drawing a circle around them; then the rest of the army was packed into that same circle section by section. After this, it was an easy matter to add up the groups of ten thousand and come up with a total figure. Other ancient sources give similarly high numbers for Xerxes' army.
Despite the manuscript evidence, many modern historians discount Herodotus' figure as highly unrealistic, positing that it would be impossible to keep such a large army supplied and watered along the route to Greece. The largest figure that they will concede for the Persian invasion army is 250,000, one tenth of Herodotus' 2.5 million. Herodotus may be lauded as the "father of history" in theory, but when it comes to counting heads, the Ph.D.'s born two and a half thousand years later consider themselves eminently more qualified.
Whenever I think about this mistrust of ancient and medieval statistics, I am reminded of the passage in Isaiah describing the Assyrian siege of Jerusalem. The Assyrian king Sennacherib taunts Hezekiah of Judah, claiming that Yahweh will not be able to deliver His people, the Jews. In response, God sends the Angel of the Lord into the camp of the Assyrians killing 185,000 men. If you believe in the inerrancy of Scripture, then here you have very clear proof of the large size of armies in ancient times. If the Assyrians could gather 185,000 men (or more) to besiege Judah in the 700s BC, why couldn't Xerxes, with his far larger empire, gather an army of 2.5 million in the 400s?
As far as the medieval chroniclers go, Steven Runciman may be right to distrust their figures somewhat. "Fulcher of Chartres and Albert of Aix tell us that the fighting men of the First Crusade numbered 600,000, while Ekkehard gives 300,000 and Raymond of Aguilers a modest 100,000." The discrepancies between these numbers are substantial; at the same time, all of the chroniclers report that the Crusader army was of exceptional size. But instead of averaging these statistics, or even taking the lowest one, Runciman upholds the modern notion that such a large number of combatants would be impossible to assemble and supply during this time period; therefore, he discards the chroniclers' statistics altogether.
Interestingly enough, Runciman goes on to say that, "when they are dealing with smaller numbers the chroniclers need not be entirely distrusted." Using these "smaller numbers" Runciman attempts to construct his own sum total of what the Crusader army could have amounted to. Whenever the chroniclers mention various contingents within the armies (e.g. Bohemond's knights, Godfrey's infantry), he pieces those numbers together. Finally, he comes to a reasonable total of "roughly 4200 to 4500 cavalry and 30,000 infantry." This number, he cautions, is only an estimate and must be taken "with reserve." A very wise caution since his opening statements claimed that it is, "impossible for us today to establish the actual size of the Crusading armies."
Although it is entirely proper for historians to compare and evaluate primary sources, it does seem rather odd to treat them with such blanket skepticism in this area. Somehow, it is considered more accurate to trust the conjecture of the modern scholar who lived one thousand years after the event than to give credence to the count of eyewitness chroniclers. We live in an age that exalts reason over revelation, and is it not perfectly reasonable to assume that the men who built catapults, castles, cloisters, and cathedrals could only count as far as their fingers and toes would take them?