Hindley - Medieval Sieges & Siegecraft

Chapter 12 : concerning the initial attack on a fortress or city. The attacker can expect the greater losses; accordingly, he aims to intimidate by display of arms and martial trumpet calls and then moves the scaling ladders against the walls. Inexperienced defenders may well surrender, but if the assault is repelled by an experienced garrison then the morale of the populace will be increased.

Chapter 14 : concerning a testudo. Vegetius describes here a wooden structure covered with leather and goats fleeces (soaked in water, presumably) so as to be proof against fire lances and arrows. Inside is a beam which may be fitted with an iron hook with which to loosen the masonry or shod with iron and called a ram because it swings back and forth in the manner of a battering-ram. But it takes its name from the tortoise, because just as that beast retracts its head within its shell and then thrusts forward, so the machine vibrates its head back and forth against the stonework.

Chapter 16 : describes musculi , which according to the description are protective wheeled sheds (the cats of medieval military men), better termed pilot fish if we are to retain the marine imagery because they advanced ahead of the siege-tower, like pilot fish ahead of a whale) protecting work parties detailed to fill in the moat.

Chapter 17 : De turribus ambulatoriis (mobile towers). According to Vegetius in earlier Roman times these structures could be from 30 to 50 square ft. at the base and so high as to overtop not just the walls but even the turrets above them. They had several levels and might have bridges protected by tunnel-like structures of twigs and branches. The topmost stage of the tower would be manned by bowmen and troops called contati (contact men, probably) armed with pikes with which they cleared the defenders from the wall by direct contact.

Chapter 18 : ways to destroy such towers include sortie by a fire detail; the use of fire darts hurled by missile throwers; by commando troops let down on ropes from the city walls at night with covered lanterns to set fire to the structure.

Chapter 19 : defenders may raise the height of the wall at the point where the siege-tower is aimed. Vegetius answer to this was to construct a siege-tower with a telescopic stage, which is sunk within the tower until the last moment when it is hauled up by ropes and pulleys to overtop the wall or its height extension. Whether such telescopic towers ever were actually deployed is doubtful.

Chapter 20 : describes a defense against a siege-tower by tunneling out from the walls once it was clear along which route the tower was to be advanced; when it reached the head of the tunnel it would sink under its own weight.

Chapter 21 : deals with the hazards of troops on scaling-ladders and attributes the invention of this mode of assault to Capaneus, an obscure hero from ancient Greek mythology whose name would have meant very little to a medieval commander. It also describes a swing bridge attachment to a siege-tower which is lowered onto the enemy wall by pulleys at the last moment and another type of bridge thrust out from the tower.

Chapter 22 : describes the ballista , a type of mounted crossbow strung with ropes made of animal sinews and which requires specially trained operatives, and the onager . The Latin means wild ass and this machine, also powered by multiple sinew cordage, Vegetius reckons the most powerful of the stone-throwers. Vegetius says nothing about how the thing actually worked; perhaps it was powered by the torsion of the twisted sinews being suddenly released.

Chapter 24 : describes two types of mining operation (alluding again to the mining industry of the Thracians, presumably the Bessi, a people of north-eastern Thrace, a region known for its mine workings): First, the piercing of tunnels under the walls through which assault parties may penetrate the town; second, the incendiary mine beneath the foundation of the walls to collapse them.

Chapter 26 : describes the maneuver of faked retirement by the besieging force. The ruse was used at Antioch in 1198 and on numerous other occasions.

Chapter 30 : how to arrive at the specifications for scaling-ladders and siege-towers. One method of measuring the height was to fire an arrow, with string attached, to the top of the battlements (presumably from as near the base of the wall as possible). A second method was to measure the length of the shadow cast by the wall and compare it with shadow cast at the same time by a rod of known length.

Vegetius ends this part of his summary of machines and maneuvers in land warfare by re-emphasizing that no amount of skill or apparatus can save a fortress that has not been properly provisioned.