Manuballista

Carroballista was an ancient, cart-mounted ballista, a type of mobile field artillery. According to the Roman author Vegetius (''Epitoma rei militaris'' II.25), each legion had 55 ''carroballistae'' (one per ''centuria'') which were arrow/bolt-shooter of the ''cheiroballistra'' () type. Vegetius tells us that each ''carroballista'' was carried by mules and operated by one ''contubernium'' (i.e., eight soldiers commanded by one ''decanus''). Surviving representation of a ''carroballista'' are from the bas-reliefs of Trajan's Column (Scene XL and Scenes LXV/LXVI) and the Column of Marcus Aurelius.

Structure

The structure of the ''carroballista'' machine is identical to that of the ''cheiroballistra'' or ''manuballista'', which translates in all its forms to "hand ballista", was an imperial-era Roman siege engine. Designed by Hero of Alexandria and mostly composed of metal (the spring mechanism and the skeins), it shot bolts that were smaller than those in other forms of ballistae and generally made of metal. It was the next major improvement after the '' scorpio''. The name of the weapon is composed of the Greek words for 'hand' and 'shooter' implying that portable versions might also have existed, similar to crossbows.

It seems that the technical innovations introduced by the adoption of the ''cheiroballistra'' by the Roman army at the end of the 1st century AD made the use of the cart possible. In fact, the light but stout metal spring-frame and the wider space in the frontal part of the machine given by the arched strut conferred a greater manoeuvrability to the whole ballista.

Shooting position

According to the Trajan's column representation (Scene XL), the ''carroballista'' was manoeuvred by one man mounted on the cart with the ballista and by another man positioned behind the cart and operating probably some sort of winch handle. The presence of the mules in front of the cart suggests that the ''carroballista'' could be easily moved through the battlefield whilst shooting bolts. This interpretation is not unanimously accepted by scholars.

It is not certain that the ''ballistae'' are actually shooting. The whole representation could be simply an image of carts transporting ''ballistae'' to their destination nest on the battlefield. But the bolts or arrows are here depicted in a ready-to-fire position, hazardous for artillerymen if the ''ballistae'' are simply being transported in order to be dismounted and deployed on the battlefield.

In another section of the Trajan's column (Scene LXVI) the simple transportation of the ''ballista'' is depicted and now we have no arrows or bolts ready to be released on the ''ballista'', the ''ballista'' is empty, and no artilleryman is manoeuvring the machine. An artilleryman is pulling the cart near the wheel and this suggests that the whole machine must have been quite a heavy structure.

Structure of the cart

It is sure that the cart was pulled by two mules or horses and that the size was probably that of standard Roman carts, i.e. c. 5 Roman feet (c. 147 cm) width (as depicted in the Trajan's Column, Scene XL and Scene LXVI), but the whole design of the cart is uncertain.

There are many hypotheses about the structure of the cart and probably different models of the same machine seem to have been in use at the same time:

* a simple two-wheel cart used to transport the ''ballista'' to its final emplacement on the field;
* a special two-wheel cart .e. ''carroballista''with a ''ballista'' mounted on the cart and with the frontal part positioned towards the mules;
* a special ''ballista'' simply mounted on two wheels and without cart (Trajan's Column Scene LXVI) and probably transported with the frontal part positioned rear, like Modern Era cannons, or forward and with a Transport-hook or Transport-hooks at the frontal position (see again Trajan's Column, Scene LXVI).About this hypothesis and a proposal of reconstruction of a ''carroballista'' of this type, see W. Soedel and V. Foley, ''Scientific American'', March 1979, pp. 150–160.
* a special four-wheel cart with a mounted ''ballista'', as described in the book ''De Rebus Bellicis''.
Many scholars do not have an opinion about this problem, due to scarce evidence, as clearly stated by Alan Wilkins.

See also

* Ballista
* Ballista elephant
* Gastraphetes
* Roman siege engines
* Scorpio (weapon)
* Tachanka

Citations

General and cited references

*Duncan B. Campbell and Brian Delf, ''Greek and Roman Artillery 399 BC–AD 363'', New Vanguard series 89, Osprey Publishing Ltd., Oxford 2003.
* J. P. Oleson, ''The Oxford Handbook of Engineering and Technology in the Classical World'', Oxford 2006, page 699.
* W. Soedel and V. Foley, ''The Greek and Roman Ballistae'', ''Scientific American'', March 1979 p. 150 – 160* A. Wilkins, ''Roman Artillery'', Princes Risborough 2003, pages 39–50. Wilkins, teacher of Classics at the University of Cambridge, produced for the first time real scale operating ''ballistae'', among which the famous stone-thrower for the BBC and a ''cheiroballistra''.

External links

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{{Ancient mechanical artillery and hand-held missile weapons

Ancient Greek artillery
Projectile weapons
Roman artillery
Roman siege engines