Siege towers, gates and drawbridges

[Eleatic Guest]

Did the Romans (or Greeks) already knew drawbridges or were they a purely medieval innovation, as usually assumed? I wonder how Roman troops got then from the siege towers onto the battlements? And how were the gates of Roman city walls located vis-a-vis the moat?

I understand there seems to be in English also a terminological ambiguity which is absent in other languages. In English, as I understand it, the term 'drawbridge' can denote both this type of bridge and that type, whereas in German, for example, the equivalent term ('drawbridge' = 'Zugbrücke') is reserved exclusively for the first type.

[Eleatic Guest]

PS: I just found a reference to ancient 'Fallbrücken' at wiki.de. In my understanding, these Fallbrücken are clear cases of drawbridges, although its important movement was to let the bridge down, not to pull it up.

So how can people assume that drawbridges were unknown in antiquity? Because they were not used in connection with city gates?

http://de.wikipedia.org/wiki/Fallbr%C3%BCcke

[Robert]

OK, I'm no expert, but in some documented cases the gap in the moat was offset to the wall, causing the attacker to move diagonally to the wall for some distance. The shift was to the left, causing the right hand side of the attacker to face the wall when passing through the gap in the moat. This was the non-shielded side, making the attacker more vulnerable to missiles from the defenders. I have once read an account (source clouded in the mist of time, sorry) of the moat opposite the gate normally being filled in with bundles of thatch, which could be set alight to restore the barrier function of the moat when attack was eminent, but have no proof of this being used in Roman times. No reference to a drawbridge is known to me for castella or castra, nor any archaeological discussion on a find at an excavated gate.

[D B Campbell]

I wonder how Roman troops got then from the siege towers onto the battlements?

Apollodorus of Damascus (c. AD 117) describes a 20ft-long (6m) drawbridge for his siege tower. It was raised and lowered by pulleys.

In the siege tower described by Vegetius (perhaps lifted from a 1st C work?), there is a choice of two alternative assault-bridges. One of these, which Vegetius calls a sambuca, is evidently the classic raise-and-lower drawbridge using pulleys. The other, which he simply calls a pons ("bridge"), seems to have been pushed forwards, perhaps on rollers.

Shameless advert: If you can lay your hands on the Osprey Greek and Roman Siege Machinery volume, you can see Apollodorus' drawbridge on p. 45 and Vegetius' siege tower on p. 31 (colour plate F, where the sambuca version is shown).

[Felix Canus]

I haven't read of Vegetius' sambuca, but he undoubtably took the term from the Greek device, which was a ladder surrounded by an armored shell, and mounted by an axle or pivot to a rolling frame. I've seen images of similar devices used well into the 1300's.

Ladders have three advantages over towers in wall assault; they are lighter and faster to carry, they are quicker and easier to build, and a ladder can be built to an estimated length while a tower height needs to be carefully coordinated with the top of the targeted wall. Of course, ladders make the soldiers extremely vulnerable.

Sambuca's were developed to resolve that. The armored shell protects the troops, it can be raised and lowered to match the height of any wall (some could be extended like a modern sectioned sliding ladder), and although it was heavier than a plain ladder, was still much lighter and easier to push around than a tower.

John Warry's "Warfare in the Classical World" has an excellent picture of a Greek sambuca on page 62.

[Eleatic Guest]

Apollodorus of Damascus (c. AD 117) describes a 20ft-long (6m) drawbridge for his siege tower. It was raised and lowered by pulleys.

Isn't it strange then that drawbridges were only used in offensive and did not find their way to city defences?

Shameless advert...

Greatly appreciated. I have the book at home, but would probably not have thought about taking a look (still too much internet-fixated in my researches, sigh).

John Warry's "Warfare in the Classical World" has an excellent picture of a Greek sambuca on page 62.

Yeah, I have it, too. Believe it or not, but I bought it last year together with the Osprey above.

Two further questions:
1. So, when were drawbridges first introduced?
2. Were there in antiquity other bridge arrangements? Swing bridges, submersible bridges, etc.?

[D B Campbell]

I haven't read of Vegetius' sambuca, but he undoubtably took the term from the Greek device, which was a ladder surrounded by an armored shell, and mounted by an axle or pivot to a rolling frame.

Vegetius explains that the assault-bridge attached to his siege tower was called sambuca because it resembled a harp: "just as there are strings on a harp, so there are ropes which lower a bridge from above by means of pulleys, so that it descends to the wall, and immediately the soldiers come out of the tower and, using it to cross over, they invade the town walls".

This is not at all like the wheeled sambuca that Damios allegedly built (and which Felix/Cedric alludes to). It is more like the shipboard version described by Polybius in connection with the Roman siege of Syracuse in 213 BC (for which it had probably been newly invented).

John Warry's "Warfare in the Classical World" has an excellent picture of a Greek sambuca on page 62.

John Warry's picture is based on Eric Marsden's translation of Biton (our only source for Damios' sambuca). I prefer to follow Otto Lendle's reinterpretation of the chassis. (See Greek and Roman Siege Machinery, p. 26 = colour plate B).

Interestingly, we have no historical evidence that this machine was ever used, unlike the shipboard version, which was obviously very useful in transferring marines onto a sea wall.

[Eleatic Guest]

Time to resurrect the topic. Archaeological evidence for Roman fortifications featuring drawbridges shouldn't be hard to come by, should it? All it takes is a moat directly located before a town gate and no traces of timber or stone pillars. That would be solid indirect evidence.

Curiously, most authors pass over the subject. IIRC, not even Baatz's otherwise detailed Town defenses in the Roman West referred to drawbridges.

[D B Campbell]

IIRC, not even Baatz's otherwise detailed Town defenses in the Roman West referred to drawbridges.

I think you have your answer, Stefan!

Off the top of my head, I know that the fort of Bar Hill has a continuous ditch cutting across the west gateway, but I think that has more to do with the steep slope on that side. (Stick a gate on that side because the plans say so, but nobody's ever going to use it.)

[Eleatic Guest]

Hehe, I found evidence for ancient swing bridges. Two were installed by Hadrian in the Teatro Marittimo across the circular moat surrounding the villa on the small island. AFAIK the first bridges of this type in history.

[jkaler48]

I suspect that drawbridges were not used in most roman fortifications for the same reason the wide double gates may have been used rather than single gates of later castles. The main intent of fortification in general must have been not to sustain a Lengthy siege but to delay an surprise attack long enough for the troops to assemble and go forth to kill the enemy or to allow re-enforcements to arrive from other forts if needed.