The ballista is one of the several Greek type of weaponry in my project. It was invented by the Greeks, as a mixture of a hand-held crossbow and a siege engine called oxybeles. In Greek warfare, this was used as a piece of artillery in battles.

How it works is that there is a large and wide spear shaped projectile loaded into the launching mechanism of the ballista. Then one soldier uses the winch to wind it up, (this decides the distance the projectile will go, and the power that will be put behind it) then a couple of other soldiers move the ballista left/right and up/down while another holds a ratchet in place to prevent the projectile from firing.  When aimed and set properly, the projectile is launched.

This weapon was used for attacking forts or other held positions of the enemy. For its time, a very effective heavy ranged weapon. Not only did the Greeks use this technology, the Romans did, and later on, several on the European kingdoms as well.

The main other use of ballista was on ships, before cannons were invented.