The advantages fortifications gave to the defenders have already been discussed. If a hasty attack failed, that demonstrated the need for the besieging army to eliminate or minimize these advantages. The most extreme example of success in this respect would be to bring down a large section of the enemy’s walls entirely, either through bombardment or, more likely, at least until the mid-fifteenth century, by deep mining. The latter technique involved digging a tunnel, just as if for an ore mine, from a covered position to underneath the targeted fortification. Only rarely was the tunnel continued to inside the walls; normally, it was instead extended laterally beneath them, with wooden props emplaced to bear the weight of the stone above. Finally, the tunnel would be partly filled with inflammables and the props oiled and set afire; once they had burned away sufficiently, the tunnel would collapse, and with it the wall.37 For “enormous oak timbers” to weaken sufficiently took some time. At Nicaea in 1097, the crusaders all, “small and great, gathered twigs, stalks and sticks and dry reeds, pieces of tow and all sorts of kindling and heaped it between the posts and beams and the splendid timbers” holding up a tower that had been undermined at its base, but by the time the edifice collapsed with a noise like thunder, it was the middle of the night, and many of them had gone to sleep.38
Deep mining might not be possible at all, for example if the local water table was too high or the town wall rested on bedrock. Even if conditions were ideal, and the attacking army was well provided with specialists who could undertake the task, deep mining was a relatively slow process, a matter of weeks or months.39 It was also not guaranteed of success, because the
Trebuchets in action at a siege, Royal MS 16.G. vi, folio 388, about 1340. (The British Library/StockphotoPro)
Defenders could countermine—dig a tunnel of their own until it intersected the besiegers’ tunnels, break in, kill the miners, and collapse the tunnel.40 Hence deep mining operations were likely to be begun at the start of preparations for a deliberate assault, but along with, rather than instead of, other methods.41
Much the same went for bombardment. Even in the early Middle Ages, some engineers were able to build Roman-style catapults and mangonels and also traction trebuchets; the twelfth century saw the counterweight trebuchet added to the arsenal, and the late Middle Ages introduced and gradually perfected cannon. The traction trebuchet was a major advance when it was introduced to Europe in the sixth century, as it was capable of firing with great rapidity and accuracy, combined with substantial hitting power.42 It was also very simple, basically a long pole like a ship’s mast43 held off-center between two uprights or trestle frames, with a crossbar at the tip of the short end of the beam to which a number of ropes were attached, and a leather sling on the other end. A crew of pullers proportionate to the size of the engine (as few as a half-dozen or so, or as many as 100 or even 250 men or women44) would haul back simultaneously on the ropes to pull down the short end, which would send the long end swinging up. When it reached the top of its arc, the missile loaded into the sling (usually a stone, often rounded by a stonemason but often not, especially for the smaller versions of the machine45) would fly off toward the target. An eyewitness describes what one of these engines could accomplish against mud-brick walls:
When it was prepared, the fenevol [traction trebuchet] fired five hundred stones per night, and a thousand per day. When the hour of vespers arrived, the fenevol had demolished so large a part of the wall that a great breach had appeared. And the cry went up amidst the army that they should go to fight, and they armed themselves and commenced the battle.
And the men of the army fought with shield and lance, alongside all the crossbowmen of the army that were there.
Throughout the battle the fenevol did not once cease firing, and so ferocious was the battle and so accurate the fenevol that a great number of those inside the town were wounded, both squires and other men-at-arms. . . . And the fenevol had made great inroads, so that because of the great amount of dust from the earth it had displaced [the castellan, defending the breach] was almost buried up to his knees.46
An engine that could launch a stone every 50 seconds or so, as the above text implies,47 obviously had a tremendous appetite for ammunition. Operating the machine was hard work, so the pulling crews had to be rotated fairly frequently. At Lisbon in 1147, the sailors, knights, and the knights’ followings were divided into groups of 100 to operate two engines. “On a given signal the first hundred retired and another took their places, so that within the space of ten hours five thousand stones were hurled.”48 Several traction trebuchets operating simultaneously could absorb the labor and time of many hundreds of pullers each day. Combine that with the efforts required to feed the engines with projectiles—work often undertaken by the army’s footmen, sometimes in return for extra pay49—and it is clear that of all siege engines, the traction trebuchet was the one that had the greatest significance for the lives of soldiers in sieges where it was present.50 In crusading situations we sometimes hear of the religious leaders offering indulgences to those participating in this work, which could lure even noblemen into manual labor:
Even the knights did not wait for soldiers to bring things, but helped in every way they could. In front of them in their saddles they would bring by horse the stones for the fenevols. And the men of their house[hold]s did the same to supply the [larger counterweight] trebuchets, delivering the stones on frames that they had tied with cords round their necks.51
Starting in the second half of the twelfth century, the largest trebuchets usually employed massive counterweights (typically, heavy timber frames filled with tons of wet earth or lead), rather than pulling crews, to launch their projectiles.52 These engines cast bigger stones greater distances but reduced the demand for soldiers’ labor since draft animals could provide the energy to raise the counterweights, and the larger missiles had to be carted, rather than carried, to the engines. Their rate of fire was also much lower, typically a dozen to a few dozen shots per day, instead of hundreds.53 Traction trebuchets did not, however, cease to be used when the newer form was introduced.
Counterweight trebuchets, which could fire stones of several hundred pounds, were capable of breaching even stone walls by prolonged bombardment.54 At the siege of Acre in 1191, after weeks of bombardment, one great machine named “God’s Stone-Thrower” reportedly opened a gap of around 30 feet in the town wall, though taken together, the sources suggest that this actually meant that the top of the wall was demolished, leaving the foundations intact to about a man’s height—still a significant barrier to an assault.55 Nonetheless, until the development of really effective siege cannon in the fifteenth century, all sorts of medieval stone-throwers were of very limited effectiveness against strongly constructed stone walls. At the siege of Dunbar in 1336, the defenders mockingly used a towel to wipe off the marks left on their walls where great stones had struck. Trebuchets and mangonels “could not damage” the monastery of Floreffe in 1189, so after seven weeks, the defenses were undermined.56 At a pair of Portuguese sieges of 1387, “[f]if-teen days passed without any thing being done: their machines were, indeed, pointed against the walls, and cast heavy stones ten or twelve times a day, but did little damage, except to the roofs of the towers, which they ruined; but the garrisons paid no attention to this, for their lodgings were well arched: and no engine nor springald could hurt them with any stones they could throw.”57
Even if they were not strong enough to batter down well-made walls, however, stone-throwers could quite effectively demolish wooden hoardings or breastworks, knock off machicolations or merlons, and sometimes shatter flanking towers, all of which greatly reduced the effectiveness of fortifications as fighting platforms for the defenders.58 When we read in the sources, as we often do, of walls “severely damaged” by the action of artillery, this is what we should usually envision, unless a breach is specifically mentioned. Ramparts weakened in these ways were still major obstacles, but they were far more vulnerable to escalade (assault using ladders), to battering with rams, or to direct undermining with pickaxes and crowbars. Damaged walls still protected the town, in other words, but could no longer so well be defended themselves. Moreover, by keeping up a continuous fire, the stone-throwing engines could prevent the defenders from making repairs to the damaged areas. Hence the operation of trebuchets and other missile engines was a key part of preparation for a deliberate assault.
Many projectiles were also directed into the town, rather than against its hard shell. Great stones smashing houses and causing some injuries and deaths served to ensure that each additional day the siege lasted would have a cost for those inside as well as those outside the walls, which was very important in keeping the pressure on for surrender negotiations. Such high-trajectory missiles could also kill any livestock left in the open and prevent the defenders from moving easily from place to place or exercising their horses.59 Although
There is no way to address the question systematically, the sources overall tend to suggest that far more stones were sent over the fortifications of towns than against them.
Another reasonably common feature of major sieges was the construction of wooden siege towers or belfries.60 These were always built high enough to overtop the walls by a good margin (at least 15 feet)—often reaching heights of 80 or 90 feet61—so that crossbowmen atop them could fire down on the ramparts and sweep them of defenders, thus allowing an escalade or direct undermining to succeed. This was in fact their main purpose, a point often misunderstood.62 Usually, they also included a drawbridge at the wall’s height so that assault troops could climb up under cover to mount the defenses. They might also have a battering ram at ground level. Normally, they were designed to be mobile so that they could be drawn right up to the curtain walls on wheels, greased rollers, or barges or ships. The ones built by the Vikings at Paris in 886 had 16 giant wheels and had room for 60 men.63
The best way to advance the siege towers was to anchor iron rings into the ground near the base of the wall, then run thick cables through them, arranged with pulleys in such a way that teams of oxen or men could haul away from the walls, out of missile range, to pull the tower in the opposite direction, or alternately, so that soldiers could move the tower forward by hauling on the ropes from a protected position inside the tower.64 These engines were, however, very vulnerable to enemy stone-throwers and often failed their intended purpose for that reason. Although they were usually wetted down and covered with raw oxhides to make them fire-resistant, they could still succumb to incendiary attacks, especially after being battered by solid missiles, which could expose broken wood. The men on the towers’ roofs, especially, would then almost inevitably be burned to death; this could make manning them quite a terrifying experience.65 On the other hand, they did sometimes lead to great successes, as in the capture of Jerusalem in 1099 or, as Froissart describes, at Ribadavia in 1386:
A large machine of timber was built, and mounted on wheels, that could be pushed anywhere. It would contain, with ease, one hundred men-at-arms, and the same number of archers; but, for this attack, it was filled with archers only, and the ditches were leveled where it was intended to pass.
When the attack commenced, this machine was wheeled up to the walls by main force; and the archers, being well provided with arrows, shot vigorously on their enemies, who returned it by throwing darts and such other missile weapons as was amazing to behold. The roof of this machine was covered with strong ox-hides to shelter the attackers from the effects of the stones and the darts. Underneath were men-at-arms well shielded, who worked hard with pick-axes, and with success against the walls; for the townsmen could not prevent them for fear of the archers, who kept them fully engaged. At length, a large breach was made in the wall, and a considerable part thrown into the ditch. When the [townsmen] perceived this, they were so dismayed, they cried loudly, “We surrender, we surrender!” No one made any answer, but the English laughed at them, and said, “These peasants have done us much mischief, and mock us by now offering to surrender, for the town is already ours.” Some of the English replied, “If you wish to say any thing to us, it must be in good French or English, for we do not understand Castilian,” and kept advancing and slaying those who were flying before them. They killed them in heaps; and that day there were fifteen hundred put to death, including Jews, many of whom were resident in the town.66
Battering rams, which also normally had a strong framework of timber to support the weight of the ram, covered with oxhides or wood to protect the operators, were another frequently used siege engine. Like the towers, these could withstand a great deal of hammering from hand-thrown missiles. Diaz de Gamez describes being in one hit by small missiles so often that it sounded like the storm that would end the world, and “a man could not hear himself speak,” yet he came to no harm.67 As with stone-throwing engines, however, their practical effectiveness does not seem to have been very great if used against well-made stone walls, and like siege towers, they were vulnerable to destruction by the defenders’ engines and by incendiary mixtures.68 In reading the chronicles, one almost gets the impression that they were used more for the sake of trying everything, and to worry the defenders, than because they were expected to accomplish anything concrete.69 The same goes for the similar wheeled sheds that were also often used to cover miners with pickaxes. Geoffrey de Charny’s phrase is telling: “to exert more pressure on [the defenders] . . . mining is carried out under the cover of devices such as sows. . . cats and belfries.”70
To have any chance of success, of course—and therefore to be effective instruments of terror—rams and towers had to be brought up directly to the enemy wall. For that to be possible, sections of the moat or ditch had first to be filled up, and filled solidly. This work was usually accomplished by soldiers bringing up bundles of sticks and vines, baskets full of dirt, and so forth, one armload at a time, under cover of some sort of mantlets (movable wooden or wicker screens). This too was hard and risky labor and sometimes earned soldiers or other workers extra pay: a penny for each three large rocks at Jerusalem in 1099, for example.71 One woman mortally wounded by an arrow while dropping a load into the moat of Acre asked that her body be used to help finish the task.72 Since wooden fill was flammable, if it was used or if timber balks were used to hold and strengthen the infill, alternating layers of dirt were also necessary, to prevent the wood from being burned up by the defenders. In addition to paths for the engines, sections of the ditch might be filled in so that cavalry could cross—because horsemen were of great value, more than might be expected, once they could get at a breach or an open gate. It took at least 15 days to fill the ditches outside Majorca in 1230 in this fashion.73 The great ramps reaching to wall tops made in similar ways that were common in ancient siege warfare seem to have fallen from use in medieval times.
World History
