The Trabuco: Seige Engine Of History

During the medieval period, the Trabuco was one of the major types of siege engine used to either break down the walls of castles and gates or to throw projectiles over them. The other major siege engine, the catapult, differs in design and does not rely on a counterweight to create the momentum and force needed to hurl projectiles as the Trabuco does. The Trabuco was a major piece of military equipment employed with regularity during the period throughout Europe and the Mediterranean but finds its origins in the Zhou dynasty in China’s 5th century BCE.

The main thrust of the Trabuco is achieved by transferring potential to kinetic energy through the use of a fulcrum. The weapon consists of a base of varying design and height that has two raised pieces or points that attach to the center of a pole along its Y-Axis. On one end of the pole there is a basket that holds the projectile and on the other end is the counterweight according to The height and mass of the counterweight will directly affect how large the projectile can be and how far it will travel.


The projectiles commonly used were made of stone, dirt, wood, shrapnel, and in some cases human and animal carrion. Once the counterweight is loosed, it will swing down and around the fulcrum rocketing the basket and projectile in the opposite direction with the projectile launching out of the basket toward its target.

The Trabuco finds its roots in ancient Chinese slingshot modification. A long piece of wood was used to increase the lever and give the projectile more kinetic energy. As the Chinese developed and improved upon the technology, knowledge of the Trabuco traveled westward coming into contact with the Mediterranean and Europe by way of the Persians and Byzantine Empire. There are historical documents placing it in both Christian and Muslim armies by the Twelfth century, though there is evidence that Viking raiders were using it as early as the siege of Angers in 873 CE according to By the fifteenth century use of the Trabuco began to dwindle and eventually die out with the advent of the gunpowder cannon.

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