New Source on Maximum Capacity of Roman Artillery

[Eleatic Guest]

Well, this primary source is not brand new, but it does seem to have received too little attention yet, perhaps because the event is recorded not in the usual Greek or Latin, but in Syriac. It is found in the chronicle of Joshua the Stylite who describes a Romano-Persian war in the early 6th century AD.

Judging from the WP entry, Joshua has a good pedigree: he was a contemporary and possibly even an eye-witness to the war and his style is sober and careful in his accounts - an Ammianus of late antiquity so-to-say. He describes a huge Roman stone-thrower at the siege of Amida (modern-day Diyarbakir):

Kawad was still fighting against Amid, and striving and labouring to set up again the mule [siege mound, see L] that had fallen in. He ordered the Persians to fill it up with stones and beams, and to bring cloths of hair and wool and linen, and make them into bags or sacks, and fill them with earth, and pile them up on the mule which they had made, so that it might be raised quickly against the wall. Then the Amidenes constructed a machine which the Persians named "the Crusher", because it thwarted all their labour and destroyed themselves. For the Amidenes cast with this engine huge stones, each of which weighed more than three hundred pounds; and so the cotton awning under which the Persians concealed themselves was rent in pieces, and those who were standing beneath it were crushed. The battering ram too was broken by the constant shower of stones which were cast without cessation; for the Amidenes were not able to damage the Persians so much in any other way as by means of large stones, because of the cotton awning which was folded many times over (the mule). Upon this the Persians used to pour water, and it could neither be damaged by arrows on account of its thickness, nor by fire because it was damp. But these large stones that were hurled from "the Crusher" destroyed both awning and men and weapons. In this way the Persians were discomfited, and gave up working at the mule, and took counsel to return to their own country, because, during the three months that they had sat before it, 50,000 of them had perished in the battles that were fought daily both by night and day.

Source: Chronicle of Joshua the Stylite, LIII

Conventional wisdom in modern books has it that Greeks and Roman artillery could shoot stones as heavy as 3 talents (72-78 kilo) and not more. However, there is evidence that they could built still larger catapults. Soedel in Ancient Catapults 1979 writes that when the torsion principle was perfected, it became possible to fire a stone weighting as much as 78 kilograms. Indeed, the Roman military engineer Vitruvius gives dimensions for catapults firing stones as heavy as 162 kilograms, although such giant machines may never have been actually constructed.

Joshua appears to be a reliable historian. Could it be that Vitruv wasn't merely showing off, but that this kind of XXL-artillery he describes was actually used on the battlefield? 300 pounds are a projectile weight of about 135 kilo - a new upper limit for Roman artillery?

[D B Campbell]

Well, this primary source is not brand new, but it does seem to have received too little attention yet, ... He describes a huge Roman stone-thrower at the siege of Amida (modern-day Diyarbakir)

You are correct that the source is not a new one, Stefan. However, it does not (imho) relate to artillery. The "Crusher" machine, in my opinion, was a crane, set up overlooking the Persian embankment in order to drop boulders onto their battering ram. Similar tactics were employed elsewhere throughout the history of ancient siegecraft. It would have been difficult (and positively hazardous) to try and use a stone-projector to perform the same feat.

Conventional wisdom in modern books has it that Greeks and Roman artillery could shoot stones as heavy as 3 talents (72-78 kilo) and not more. However, there is evidence that they could built still larger catapults. Soedel in Ancient Catapults 1979 writes that ... the Roman military engineer Vitruvius gives dimensions for catapults firing stones as heavy as 162 kilograms, although such giant machines may never have been actually constructed.

Vitruvius certainly does claim that a 360-pounder could be built. I'm not sure that anyone has actually said that 3 talents (240 pounds = 78kg) was the maximum. In my Osprey book, I show a hypothetical reconstruction of the 3-talent stone projector that Diodorus attests to Demetrius Poliorcetes having used (p. 27 plate C; it can also been seen reprinted by Glenn Bugh in the Cambridge Companion to the Hellenistic World, 2006, p. 283). It is interesting that Philon's list of Hellenistic stone-projectors ends with the 3-talent machine. You can see that it is a gigantic monster. Anything designed to shoot stones weighing 4.5 talents must have been truly humongous!

[Eleatic Guest]

The "Crusher" machine, in my opinion, was a crane, set up overlooking the Persian embankment in order to drop boulders onto their battering ram.

Now that you mention the crane, I find this explanation also more convincing. A catapult would have had an absurd angle, practically engaging in plunging fire, to hit a battering ram brought in position so close to the wall (assuming it was set up somewhere in the city perimeter and not on the walls where I cannot imagine how it could have shot downwards a projectile so heavy).

I'm not sure that anyone has actually said that 3 talents (240 pounds = 78kg) was the maximum.

My impression is that this is the upper limit based on reasonable evidence beyond which modern experts start to feel uncomfortable.

The one thing I have always wondered is that in your Osprey book (p. 20) you have listed the stone shots of various ancient arsenals. Among them are altogether 3 stone balls of around three talents. Now assuming that these were also intended for being hurled by catapults, and not for dropping down on enemies from walls or an elevated position, why are they so few? This makes no sense because based on the nexus between spring diameter and projectile weight, one would need for shooting this caliber a torsion stone-thrower of its own. And once you have gone to the trouble of building one, it would be not rational to carve only a couple stone balls for them.

[Ildar]

300 pounds are a projectile weight of about 135 kilo

No, Stefan, c. 98 kg. As far as I know, in the text λίτρα = libra = 327,4 g.

[D B Campbell]

The one thing I have always wondered is that in your Osprey book (p. 20) you have listed the stone shots of various ancient arsenals. Among them are altogether 3 stone balls of around three talents.

I listed all the "ballista balls" that were then published, Stefan. I know that larger boulders were discovered (e.g.) at Masada (see here; I have not yet digitized my own slide of these stones), but are usually assumed to have been for rolling/dropping. Actually, I tend to agree with this, as I cannot imagine that many people had the resources or the inclination to manufacture a ballista large enough to shoot these stones! (Demetrius Poliorcetes is an obvious exception, but even he seems to have stopped at 3 talents!)

(Incidentally, I see that, on p. 21, I am guilty of assuming that 3 talents was more or less the limit! :errr: Actually, I still stand by that. I cannot imagine who would have had the need to manufacture Vitruvius' 360-pounder!)