Siege Engines during the Crusades

By Danièle Cybulskie

Despite what we often see in the movies, the most frequent form of warfare in the Middle Ages was siege warfare. This involved surrounding the enemy’s castle, town, or fortress, and either breaching the walls or starving the occupants into surrendering. As with any form of warfare, however, the strategies involved depended heavily on local terrain and resources.

With the twelfth century came the rise of the counterweight trebuchet, a siege engine which used gravity to swing down one end of a long beam loaded up with weights, while swinging the other end up, launching a projectile from a sling. The trick with a trebuchet – like any siege engine – is to be able to launch the projectile far enough to affect the enemy without being within range of their own siege engines or archers. In the early days of the trebuchet, the goal wasn’t necessarily to batter the walls of a fortress, but rather to launch above and over the walls, hitting enemy soldiers with stones or littering their streets with corpses, instead.


Trebuchets, like mangonels and other siege engines, were constructed out of wood, and most often built once the besieging army had set up camp. Ideal conditions meant a significant amount of wood was accessible by the besieging army for fires, support beams for undermining, and (of course) building siege engines. After the siege was ended – either successfully or unsuccessfully – the engines were usually destroyed, or the parts reused. (As Robert the Bruce believed when he razed Scotland’s castles, it was good policy not to leave anything behind that could be used against you in future.) But as sieges became more frequent in places where wood was scarce, medieval strategists began to see the wisdom of prefabricating their siege engines and bringing them from place to place.


13th century depiction of the Siege of Acre during the Third Crusade – Biblotheque Municipale de Lyon, Ms 828 f33r

In the Holy Land during the eleventh to fourteenth centuries, it seemed as if one place or another was continually under siege, and armies on both sides of the crusades moved from city to city attempting to dominate each other. In his article “Development of Prefabricated Artillery During the Crusades”, Michael S. Fulton explores how crusading armies learned from one another how best to create and use their siege artillery in a land in which wood was relatively scarce.


Fulton notes that both Damascus and Jerusalem kept stockpiles of wood (likely for more than one use), and that increasingly siege engines were stored at Damascus for deployment elsewhere by Muslim armies. It’s unlikely that they were kept in their assembled form, but the simplicity of their design would allow for quick construction. In fact, Fulton writes, in his siege of Jaffa, Saladin’s army was able to put together four siege engines within three days. Although this involved his men “working through the night”, creating four complete siege engines from trees to fully-assembled machines strains belief. It’s much more likely that the pieces were brought ready-made, from Damascus or elsewhere.

Richard I, too, seems to have brought ready-made pieces of siege engines on his journey to Acre from Sicily, a move that makes sense, as Fulton notes, because there were many more trees to be found in Sicily. Upon successfully taking Acre, Richard sailed his siege engines down the coast of the Holy Land rather than trying to have them carried over land. A century later, Fulton remarks, Mamluk soldiers would be tasked with carrying the components of siege engines up to Acre from Damascus on their shoulders. No doubt they would have much preferred a boat.

Interestingly, it wasn’t always the siege engines, themselves, which were brought from a distance. As Fulton says, “Although the notion of importing projectiles may seem far-fetched, there is evidence for a precedent in the Sicilian siege of Alexandria in 1174…. Along with its three stone-throwing engines, this force brought conspicuous black stones that were thrown with apparent effect.” These black stones were “the island’s hard volcanic rock [which] would add a considerable advantage when cast against the soft kurkar fortifications of the Palestinian coast;” therefore, he suggests, they may have been an option for Richard I, as well, when he left Sicily. While rocks would have been much easier to find than trees at the site of a siege in the Holy Land, transporting rock which would have had a much better chance of breaking walls must have seemed a worthwhile option.

As Fulton says, the smaller trebuchets used in the Holy Land gave way in Western Europe to much larger, heavier trebuchets leading into the fourteenth century; trebuchets whose function was increasingly to batter a fortress’ walls, themselves, and either breach them or intimidate the enemy into surrendering, as Edward I did with the massive trebuchet “War Wolf” used against Stirling Castle. But though wood was much more plentiful in Western Europe than it was in the Holy Land, and therefore building siege engines on the spot much more feasible, it seems that those who had been on crusade had learned their lessons well from opponents such as Saladin, whose ability (Fulton notes) to reuse his siege engines allowed him to attack city after city in succession. In the late twelfth and thirteenth century, Fulton cites three different crusader kings using premade parts in their sieges at home: Richard I, Philip Augustus, and Louis IX.


As the fourteenth century arrived and kings like Edward I were building massive trebuchets with or without prefabricated parts, the trebuchet’s day was waning. Soon, a new weapon would replace the trebuchet, in part because of its relative ease of transport and the fact that it didn’t rely on local resources for its creation. That weapon was the cannon.

For more on the use of artillery in the crusades, you can find Michael S. Fulton’s full article “Development of Prefabricated Artillery During the Crusades” in the Journal of Medieval Military History (XIII). You can also read his book Artillery in the Era of the Crusades: Siege Warfare and the Development of Trebuchet Technology or follow him on

Danièle Cybulskie is the Lead Columnist on and the host of The Medieval Podcast. You can follow her on Twitter @5MinMedievalist


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Top Image: Detail from the Morgan Bible