The Trabuco served as a form of catapult-like siege weapon in medieval times. It was developed to break down the fortified exteriors of enemy walls, as well as to fling objects over the walls. Its major advantage was its simple but effective operation. Projectiles launched from the mechanism could damage or destroy masonry of the enemy much more efficiently and quickly than by other means.
The ability of the Trabuco to hurl very heavy objects at great distances at the enemy was the secret behind its prominent use. The key to accomplishing this was the use of a counterweight that was heavy enough to generate the force heavy enough to launch a large projectile to the target. The elements needed to produce this effect (to transfer potential gravitational energy into kinetic energy) were calculated into the design of the mechanism.
Originally, the counterforce energy needed to operate trabecles came from humans. Several workers, by some designs 250 persons, had to pull the beam mechanism to hurl the projectile. Arabs later improved the mechanism by adding more weight to the short end of the device, thereby adding to the range of the weapon (from being able to send 140 pound objects up to 400 pound items).
A hybrid version of the trabuco was developed in Europe, involving more weight and use of people, to further increase the accuracy of the weapon. The counterweight generated came to be called a blunderbuss. In the 1200s, the device in time became versatile enough that it could throw objects of various kinds, from stones or cannonballs, to large animals, human body parts, or even living people against an enemy target.
After being a highly dominant weapon for 300 years throughout Europe, interest in the employing the large device began to wane, due to the creation of gunpowder. At that point, use of the trabuco came to be viewed as old-fashioned and fell out of favor.