Editing Roman siege engines (section)

====Early Roman ''ballistae''====
[[Image:047 Conrad Cichorius, Die Reliefs der Traianssäule, Tafel XLVII (Ausschnitt 02).jpg|thumb|199px|Roman 'catapult-nest' on [[Trajan's Column]]]]

[[File:Ballista (PSF) vector.svg|thumb|left|''Ballista'']]

The early Roman ''ballistae ''were made of wood, and held together with iron plates around the frames and iron nails in the stand. The main stand had a slider on the top, into which were loaded the bolts or stone 'shot'. Attached to this, at the back, was a pair of [[winch]]es and a claw, used to [[ratchet (device)|ratchet]] the bowstring back to the armed firing position. A slider passed through the field frames of the weapon, in which were located the torsion springs (rope made of animal [[Tendon|sinew]]), which were twisted around the bow arms, which in turn were attached to the bowstring.

Drawing the bowstring back with the winches twisted the already taut springs, storing the energy to fire the projectiles.

The ''ballista'' was a highly accurate weapon (there are many accounts right from its early history of single soldiers being picked off by the operators), but some design aspects meant it could compromise its accuracy for range. The lightweight bolts could not gain the high momentum of the stones over the same distance as those thrown by the later [[onager (siege weapon)|onager]]s, [[trebuchet]]s, or [[mangonel]]s; these could be as heavy as {{convert|90–135|kg|abbr=on}}.

The Romans continued the development of the ''ballista'', and it became a highly prized and valued weapon in the army of the [[Roman Empire]].

It was used, just before the start of the empire, by [[Julius Caesar]] during his conquest of [[Gaul]] and on both of his expeditions to Britain. Both attempted invasions of Britain and the siege of Alesia are recorded in his own ''[[commentarii]]'' (journal), ''The [[Gallic Wars]] ''(''[[Commentarii de Bello Gallico|De Bello Gallico]]'').