Editing Roman siege engines (section)

===''Ballista''===
{{Main|Ballista}}

[[File:Young Folks' History of Rome illus103.png|thumb|left|Roman arrow machine]]

[[File:Bal BBC1.jpg|thumb|One [[Talent (measurement)|talent]] ''ballista'' (26 kg weight projectile). The heaviest versions could shoot up to three talents (78 kg), possibly much more.<ref>Werner Soedel, Vernard Foley: “Ancient Catapults”, ''[[Scientific American]]'', Vol. 240, No. 3 (March 1979), p.120-128 (121ff.)</ref>]]

[[Image:ballista.gif|thumb|right|A ''ballista'']]

After the absorption of the ancient Greek city states into the [[Roman Republic]] in 146 BC, some advanced Greek technologies began to spread across many areas of Roman influence. This included the hugely advantageous military advances the Greeks had made (most notably by Dionysus of Syracuse), as well as all the scientific, mathematical, political and artistic developments.

The Romans 'inherited' the torsion powered ''ballistae'' which had by now spread to several cities around the Mediterranean, all of which became Roman spoils of war in time, including one from [[Pergamum]], which was depicted among a pile of 'trophy' weapons in relief on a balustrade.

The torsion ''ballista'', developed by Alexander, was a far more complicated weapon than its predecessor, and the Romans developed it even further.

[[Vitruvius]], in his ''[[De Architectura]]'' book X, describes the construction and tuning of ''ballistae''.

Every [[centuria|century]] (group of 60-100 men) in the Roman army had a ''ballista'' by the 1st century AD.<ref>Le Bohec 1994: p. 138</ref>  It was the command of the chief of the ''ballistae'', under whom were the artillery experts, or ''doctores ballistarum'' and finally, the artillerymen, or ''ballistarii''.<ref>Le Bohec 1994: p. 49</ref> ''Ballistae'' were heavy missile weapons, hurling large rocks great distances to damage rampart walls. They resembled large [[crossbow]]s, rather than [[catapults]]. They were powered by two horizontal like arms, which were inserted into two vertical and tightly wound "skein" springs contained in a rectangular frame structure making up the head or principal part of the weapon.  The arms were drawn rearward with a winch lever to further twist the skeins and thus gain the torsion power to cast a projectile.<ref name="legionxxiv"/> It has been said that the whirring sound of a ''ballista'' projected stone struck fear and dread into the hearts of those inside the walls of besieged cities.  The stones chosen to be used in the ''ballista'' had to be a particular sort.  According to [[Publius Flavius Vegetius Renatus|Vegetius]], river stones were best, since they are round, smooth, and dense.  ''Ballista'' stones found at the site of [[Masada]] were chiseled to make them as round as possible.<ref>Garrison 1997.</ref>

====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]]'').

====First invasion of Britain====

The first [[Roman conquest of Britain|invasion of Britain]] took place in 55&nbsp;BC, after a rapid and successful initial conquest of Gaul, in part as an exploratory expedition, and more practically to try to put an end to the re-enforcements sent by the native [[Brython|Britons]] to fight the Romans in Gaul.

A total of eighty transports, carrying two legions, attempted to land on the British shore, only to be driven back by the many British warriors assembled along the shoreline. The ships had to unload their troops on the beach, as it was the only one suitable for many kilometers, yet the massed ranks of British [[chariot]]eers and javeliners were making it impossible.

<blockquote>Seeing this, Caesar ordered the warships – which were swifter and easier to handle than the transports, and likely to impress the natives more by their unfamiliar appearance – to be removed a short distance from the others, and then be rowed hard and run ashore on the enemy’s right flank, from which position the slings, bows and artillery could be used by men on deck to drive them back. This manoeuvre was highly successful.<br /> Scared by the strange shape of the warships, the motion of the oars, and the unfamiliar machines, the natives halted and then retreated a little. (Caesar, ''The Conquest of Gaul'', p. 99)</blockquote>

====Siege of Alesia====

In Gaul, the stronghold of [[Alesia (city)|Alesia]] was [[Battle of Alesia|under a Roman siege]] in 52 BC, and surrounded by Roman fortifications. As was standard siege technique at the time, ''ballistae'' were placed up in the towers with other soldiers armed with either [[bow (weapon)|bow]]s or [[sling (weapon)|slings]].