Roman siege engines
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Roman siege engines were, for the most part, adapted from Hellenistic siege technology. Relatively little was done on their part to develop the technology, however the Romans brought an unrelentingly aggressive style to siege warfare (Goldsworthy 2000: 144). Caesar looked at war as a means of conquering and establishing Roman rule over new territories, bringing wealth to those serving in the field as well as citizens of the empire. He also knew that success in the field would increase the loyalty of his soldiers, allowing for more territory to be conquered through continued service. To this end, he took great interest in the integration of siege engines , organizing their use for optimal battlefield efficiency (Keppie 1984: 99).
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[edit] Army engineering corps
To facilitate this organization and the army’s self-sufficiency, an engineering corps was developed. An officer of engineers, or praefectus fabrum , is referenced in armies of the Late Republic , but this post is not verifiable in all accounts and may have simply been a military advisor on the personal staff of a commanding officer (Keppie 1984: 99). There were legion architects (whose rank is yet unknown) who were responsible for the construction of war machines who would also assure that all artillery constructions in the field were level. Ensuring that constructions were level was the job of the libratores , who would also launch missiles and other projectiles (on occasion) during battle (Le Bohec 1994: 52). The engineering corps was in charge of massive production, frequently prefabricating artillery and siege equipment to facilitate its transportation (Goldsworthy 2000: 144).
[edit] Artillery
During a siege the Romans would attack the weakest area of their enemy’s defenses and attempt to breach the wall(s) there. To support this effort, artillery fire would commence, with three main objectives (according to Le Bohec 1994: 138); to cause damage to defenses, casualties among the opposing army, and loss of morale. It would also provide cover fire for troops building siege ramps or in siege towers. There were machines called tormenta , which would launch – sometimes incendiary - projectiles such as javelins, arrows, rocks, or beams. These devices were on wheeled platforms, to follow the line’s advance. All were, “predicated on a principle of physics: a lever was inserted into a skein of twisted horsehair to increase torsion, and when the arm was released a considerable amount of energy was thus freed” (Le Bohec 1994: 138). It was later stated that sinew, instead of twisted hair provided a better “spring.” These weapons could be high-maintenance devices and were vulnerable to having their leather or sinew or hemp skeins get wet or even damp, which would cause them to slacken and lose tension, rendering the engine useless (http://www.legionxxiv.org/catapulta/).
It is somewhat difficult to clearly define and describe Roman artillery , as names are easily confused and historians still do not agree on all definitions. Perhaps best known are the ballista, the onager, and the scorpio.
[edit] Ballistae
After the absorption of the Ancient Greek City states into the Roman Republic in 146 BC, the highly advanced Greek technology 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.
Every century (group of 100 men) in the Roman army had a ballista by the First Century (Le Bohec 1994: 138). It was the command of the chief of the ballista, under whom were the artillery experts, or doctores ballistarum and finally, the artillerymen, or ballistarii (Le Bohec 1994: 49). Ballistae were heavy missile weapons, hurling large rocks great distances to damage rampart walls. They resembled large crossbows, 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 principle 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 (http://www.legionxxiv.org/catapulta/). It has been said that the whirring sound of a ballista-fired stones 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 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 (Garrison 1997).
[edit] Early Roman ballista
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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 Winches and a Claw, used to ratchet the bowstring back to the armed firing position. slider passed through the field frames of the weapon, in which were located the torsion springs (rope made of animal 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.
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The ballista was a highly accurate weapon (there 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 onagers, trebuchets, or mangonels; these could be as heavy as 200-300 pounds (90-135 kg).
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 campaigns in conquering Britain. Both attempted invasions of Britain and the siege of Alesi are recorded in his own Commentarii (journal), The Gallic Wars (De Bello Gallico), now translated and published many times.
[edit] First invasion of Britain
The first invasion of Britain took place in 55 BC, after a rapid and successful initial conquest of Gaul, in part as an exploratory expedition to see the land across the sea, and more practically to try and put an end to the re-enforcements sent across by the native Britons to fight the Romans in Gaul.
A total of eighty transports, carrying two legions attempted to land on the British shore (the eighteen accompanying cavalry transports had been blown off course on the way over), 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 miles, yet the massed ranks of British charioteers and javeliners were making it impossible.
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.
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, p99)
[edit] Siege of Alesia
In Gaul, the stronghold of Alesia was under a Roman siege in 52 BC, and was famously almost completely surrounded by a fourteen mile long trench filled with water diverted from the local river, then another trench, then a wooden palisade and towers, then the besiegeing Roman army, then another series of palisades and trenches to protect them from any Gallic relief forces. As was standard siege technique at the time, ballistae were placed up in the towers with snipers (armed with either bows or slingshots).
[edit] Sources
In Gaul (France), the stronghold of Alesia was under a Roman siege in 52 BC, and was famously almost completely surrounded by a fourteen mile long trench filled with water diverted from the local river, then another trench, then a wooden palisade and towers, then the besiegeing Roman army, then another series of palisades and trenches to protect them from any Gallic relief forces. As was standard siege technique at the time, ballistae were placed up in the towers with snipers (armed with either bows or slingshots).
[edit] Onagers
According to Vegetius, each cohort had an onager, for a total of ten per [legion]] (Le Bohec 1994: 139). It’s name comes from the Latin word for “wild ass,” as the onager would rear up and kick up when discharged. The onager was a simpler version ballista. It had only one large skein placed horizontally within the frame with a large vertical arm, usually with a sling attached at its upper end (http://www.legionxxiv.org/catapulta/). It has been hazarded that catapults were used to for direct trajectory, while ballista were used for curved trajectory (Le Bohec 1994: 139). Aside from large stones, the onager could also be loaded with the equivalent mass of smaller stones or fiery pitch to use against enemy troops or to bombard the inside of a fort. Its range was much shorter than that of the ballistae and could be in danger of attack by enemy artillery during a siege (http://www.unrv.com/military/artillery.php).
[edit] Scorpions
The scorpio was a crossbow-like device that fired smaller arrows with deadly accuracy (Keppie 1984: 99) used both in the field and in sieges. They were so-named for their deadly, armor-piercing sting and could be operated by just one or two men. Scorpions were meant to kill and injure enemy forces, rather than break down enemy fortifications. Due to their smaller size, they would be mounted on or in siege towers. During the Siege of Amida, a scorpion-fired arrow killed the son of Grumbate, king of the Chionitae, when he was approaching the city to surrender (Goldsworthy 2000: 191). There has been some research done into the existence of the self-loading, serial-fire scorpio. Legionaries either side would continuously keep turning cranks which turned a chain, which operated the various mechanisms to load and fire the catapult. All that was needed was for another soldier to keep feeding in more arrows (http://www.roman-empire.net/army/leg-siege.html).
[edit] Breaching the walls
A gold walled or mural crown, called the ‘’corona muralis’’ was awarded to the first man who captured the wall of an enemy city. Livy reports that in 210 BC, at the capture of New Carthage, this honor was claimed by both a legionary centurion and a marine. In order to avoid a near mutiny from the ferocity of the resulting dispute between legionaries and marines both men were eventually awarded a crown (Gilliver 1999: 141).
[edit] Battering rams
Roman battering rams, or aries was an effective weapon for breaking down an enemy’s walls as well as their morale. Under Roman law, any defenders who failed to surrender before the first ram touched their wall were denied any rights (Goldsworthy 2000: 145). The moment they heard the ram hit the wall, those inside the city knew that the siege proper had begun and there was no turning back (Gilliver 1999: 140).
Josephus describes the battering ram used at Jotapata thus (Le Bohec 1994: 139):
“It is an immense beam, similar to a ship’s mast, with one end covered with iron shaped into a ram’s head; hence its name. It is suspended from another beam like a balance arm by cables around its middle, and this in turn is supported at both ends by posts fixed in the ground. It is drawn back by a huge number of men who then push it forward in unison with all their might so that it hits the wall with its iron head. There is no tower strong enough nor any wall thick enough to withstand repeated blows of this kind, and many cannot resist the first shock.”
For protection, a battering ram was suspended in a mobile shelter called a tortoise, or testudo. According to Vegetius, it was given this name because the ram would swing out of the shelter much like a tortoise’s head comes out of its shell. Such shelters would provide the men underneath protection against missiles and incendiary devices. They were constructed from a framework of strong timbers with planks and wicker hurdles on the sides. The entire shelter would then be covered with a fireproof material such as uncured hides (Gilliver 1999: 134-135). According to Apollodorus, the shelter should be fixed to the ground while the ram was being used to both prevent skidding and strain on the axles from the weight of the moving apparatus. This would also increase the strength of the impact on the walls (Gilliver 1999: 138).
[edit] Siege Towers
According to Josephus, the Roman siege towers at Jotapata were 50 feet high and iron-plated to protect them from fire; those at Masada were reported to be 75 feet high. It was possible to have many different devices on siege towers, such as artillery, draw bridges and rams. Those at the top of the tower were to keep defenders off the walls while those below them attempted to breach the wall using ramps (Gilliver 1999: 136-137). Following a basic design, details of tower construction varied from siege to siege and there is no known-of treatise which specifies at which level siege equipment should be placed. Vegetius noted that, “besiegers sometimes built a tower with another turret inside it that could suddenly be raised by ropes and pulleys to over-top the wall” (Gilliver 1999: 138).
[edit] Mines
Mines could be dug under city walls as a means of entering a city secretly and capturing it but were more frequently constructed to weaken city walls. Once dug, sappers would underpin the walls with wood and cause the walls to collapse by firing the supports with resin, sulfur and other incendiary materials (Gilliver 1999: 140).
[edit] Notes
[edit] References
[edit] Primary Sources
(none yet)
[edit] Secondary Sources
- James V. Garrison (1997). "Casting stones: ballista, stones as weapons, and death by stoning". Brigham Young University Studies 36 (3): 351-352.
- Gilliver, C.M. (1999). The Roman Art of War. Charleston, SC: Tempus.
- Goldsworthy, Adrian (2000). Roman Warfare. London: Cassell.
- Keppie, Lawrence (1984). The Making of the Roman Army from Empire to Republic. Totowa, NJ: Barnes & Noble Books.
- Le Bohec, Yann (1994). The Imperial Roman Army. London: B.T. Batsford Ltd..
[edit] External links
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[edit] See also
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