Authored By Staff Writer (Updated: 4/8/2013): The ballista was an artillery weapon first reported in ancient times and heavily associated in the West with the Roman Republic. For the sake of generality, the ballista here is attributed to the medieval age as early as the Eleventh Century. Various forms of the ballista appeared all across the ancient and medieval landscape, thusly no attempt here is made to distinguish one design over another as most operated on the same concept, though many might have been constructed in slightly different manners.
The ballista operated as battlefield artillery before the advent of gun powered-operated artillery pieces seen at the end of the Medieval Age. The ballista was built of various wood and metal pieces and could be operated as a mobile wheeled weapon or a weapon carried into battle.
The strength of the ballista lay in the ability to heave large spears (or bolts) at formations of massing infantrymen. The bolt was long enough and powerful enough to pierce through several men in one shot and, when weather permitted it, the ballista could be an extremely reliable and accurate weapon.
Crewed by as little as two infantrymen, the ballista was built as what one might describe a "giant crossbow". The word ballista actually has an ancient reference to the word "crossbow". Seeing it that the ballista operated on the same principle of torsion (as opposed to tension found in the bow and arrow concept) it is not a far realization to see the similarities between the two weapons.
Operation of the ballista was accomplished by turning a large four-spoke crank usually at the rear of the weapon, tightening the rope (or animal sinew in the ancient Roman cause) hereby drawing back the winch. The designated ammunition loader would drop the bolt or spear into the launching cradle and the firer would release the tension trigger, effectively launching the spear toward the enemy at a frightening velocity. The ballista could be counted on to skewer enemies from afar, and could even be used in siege warfare as a psychological tool by bringing down chunks of wall.
Naturally, a wheeled version of the ballista could be more mobile on the everchanging battlefield, able to compensate for directional changes in the enemy formations. The system, however, did not operate well in damp or wet weather, particularly those made of animal sinew, as the sinews had a tendency to snap or lose their tension over the course of a fight. As might be expected, the ballista also made for a poor close-range weapon and would have to be abandoned in the case that the position of the ballista was overrun. Targeting individuals would also not play to the ballista's strength. Operation late in a melee battle would render the ballista's principle utterly useless as well, for the fear of impaling friendly troops of the weapon was fired into the entangled crowd.
A trained crew could fire off enough bolts to warrant the system a "repeating" or "semi-automatic" designation, though this would assume that the system was in pristine condition and the crew highly trained in their craft.
In the end, this simple feat of engineering provided battlefield commanders the ability to wreak ranged warfare before the advent of gun powder artillery. Until then, the ballista could still be used to tremendous effect, particularly against large masses of moving troops or cavalry.