The Trabuco: Doomsday Weapon Of The Middle Ages

It was the doomsday weapon of the Middle Ages. With the power to blast through thick stone walls from a previously impossible distance, the trabuco, also called a trebuchet, effectively forced the architects and engineers of the Middle Ages to radically rethink their approaches to castle defense.

What Is a Trabuco?
A trabuco was a medieval weapon that developed as an extension of ancient hunting tools such as atlatls, slings, or any other weapon used to extend the throwing power of the human arm. The typical trabuco consisted of a solid wooden frame, a long lever arm, an attached sling holding a projectile, and the key to the weapon: a massive counterweight swinging on the opposite end of the lever like a giant’s basket.

How Do You Use a Trabuco?
Typically, the trabuco was assembled during the siege or even constructed on site using available lumber and rocks. Once the trabuco was ready, a projectile would be loaded into the sling and hooked to the end of the long lever arm. The enormous swinging basket of the counterweight on the short end of the lever would be filled with rocks or other heavy material and then hoisted into the air. When the trabuco was ready to be fired, ropes holding the sling end of the lever would be cut. The counterweight would abruptly pull the lever down, and the projectile rock would be whipped into the air at the target.

Facts and Figures
On average, a trabuco was generally designed to throw stones of about 50-100 kilograms, but some could throw projectiles as large as 1500-1800 kg. Even a fortress like Scotland’s Stirling Castle was no match for the siege engine called the Warwolf. Accurately throwing stones of around 136 kg, the Warwolf destroyed the outer curtain wall and effectively ended the battle right there. According to, a key factor in the trabuco’s effectiveness was its incredible range, 300 meters on average, the rough size of three American football fields. This range rendered defenses such as moats, intended to keep out armed soldiers and horses, essentially useless.

Psychological and Biological Warfare
It goes without saying that the trabuco was also used for psychological and biological warfare on Crucial to the success of a siege — at least from the besiegers’ point of view — was a quick victory, since long-term occupation of an area usually meant increased possibility of death from starvation or diseases caused by tainted water and crowded conditions at In addition to stones, trabucos could also throw dung, burning pitch, or the bodies of the dead over the walls to distribute contagious disease or simply to horrify and disgust the enemy inside, weakening their morale.

How the Trabuco Changed Architecture
The trabuco exerted a profound effect on medieval castle architecture as defenders sought to prevent themselves from being reduced to rubble. Concentric moats were constructed for distance, and castle walls were built thicker. Round towers that made projectiles bounce off at an angle began to be the norm, and the first sultan of Egypt and Syria, An-Nasir Salah ad-Din, better known in the West as Saladin, developed a strategy of using counter-trebuchets mounted on top of castle towers to fire back at a besieging army or take down the other side’s trebuchets.

The Trabuco: A Mighty Weapon
Even after the widespread popularity of cannon, the trabuco continued to be used for a long time. Its ease of assembly, its complicated physics, and most of all, its devastating effectiveness made the trabuco the apex of medieval siege engine technology on