Comitatus Ballista

Back in early 2005, Comitatus decided that we should invest in Roman artillery. It was felt that artillery would add a new dimension to shows, and increase the public appetite for what we do. We chose to bend our efforts towards a Late Roman iron framed ballista. And therein lies a universe of discussion, argument and counter argument.

A Greek document “Heron’s Construction and Dimensions of the Cheiroballistra” describes eight mechanical parts, each described with a coloured diagram. Discovered in 1843, it was largely discredited until Dr. Eric Marsden identified it in 1971 as a description of a bolt shooting catapult, with metal frames and an arched strut, identical to those on Trajan’s column.

The introduction of such machines can be dated to the end of the 1st century AD, and they are recorded as being in use 1,000 years later. But there is more than one way of interpreting the document, and current reconstructions vary in size, design and capacity. Various other writers can be used to fill in some blanks, but there are issues around interpretation.

Heron’s measurements produce a small hand portable machine. They are of relatively low poundage, but are viable weapons and could be the “hand shooters or scorpions” mentioned in Vegetius, with no stands or winches. However, fourth century archaeological finds from the Roman fort at Orsova, Romania do suggest much larger measurements for some parts of the machine, Heron himself mentions winches in connection with torsion catapults, and the measurement given for the cross-section of the wooden case is 25% larger than for the old fashioned Vitruvian scorpio, suggesting the weapon is correspondingly more powerful.

The new design allows the arms to move through a greater arc, by borrowing the palintone style frame used on stone throwing ballistae. But the spring frames are moved further apart giving greater power. Some have suggested the arms could swing inwards to increase the distance the arms travel and so generate more force. This is a 19th century idea, and some archaeological finds seem to support the theory. Some testers claim that this is a more efficient system however, it is hard to believe that much of this greater swing would not be wasted until the bolt is actually propelled forward. The jury is still out.

Many reconstructions use a simple winch system to pull back the trigger mechanism. The ratchet and pawl system used on our example folows Heron's gastraphetes. It is an authentic and, importantly, a safe system, despite the 700lb plus draw weight. There are other possible interpretations, for example from the illustration on the “Cupid Gem”, a seal stone showing a side view of a Roman catapult, with a ratchet-wheel. Ammianus Marcellinus says "two wooden rollers (cochleae duae ligneae implying a spiral or screw shape) are very firmly attached, and near one of them stands the gunner who aims the shot... strong young men quickly turn the rollers (rotabilem, derived from rota, wheel). When the catch is released, these ropes drive out the arrow."

In the future it would be interesting to field different interpretations of the iron framed design. However, for our first machine we followed the work of Alan Wilkins and our machine was constructed by Len Morgan, a well respected Roman artisan. He was a gentleman throughout and his knowledge and expertise is second to none. There are relatively few compromises in our design, and the performance is excellent.

Modern nylon rigging rope is used in the springs. It has to be pre-stretched so when it is placed under tension no power is wasted. We haven't painted or dyed the rope black to look more authentic: we want the public to notice it. We explain how Romans used rope made from animal sinew, which would have had better performance than our modern substitute, but was prone to 'catastrophic failure'. This is a working reconstruction of how things worked, safe to operate near the public. The machine is easily repaired in the field. New arms and whole spring assemblies could be easily fitted into a broken machine. The arched strut allows for accurate aiming, but the bolt cannot hit the frame in transit, as with earlier designs.

After seventeen months the iron framed ballista arrived on a hot July day, just two days before the naming ceremony. The trials of pre-stretched rope, of exploding moulds, and messing around with the size of the wooden stand were left behind. After some quick tests on York Knavesmire, the proving ground for so much Comitatus equipment, the ballista was ready for the great naming ceremony.

It was 25 July 2006, and 1,700th anniversary of Constantine the Great's proclamation as Emperor by the legion in York. It was a work day but we had still assembled a good size honour guard to escort the procession of the Archbishop and leading bigwigs around the city. The city's celebration of Constantine in dance, art and it's peoples hopes for the next 1,700 years sat uncomfortably with the reality of the actual event. However, we played our part, tried to fill in any awkward gaps, looked smart and represented the men who changed the history of the Western world that day, so long ago.

After several hours out in the heat and sun we formed up and marched through the crowds to the Roman Baths public house, and downstairs to the Bath House Museum. Graham Harris had kindly lent us his museum for the naming ceremony, and the enclosed underground space made it feel very intimate and special.

We had never done anything so formal before and it could have been a flop. But the whole thing was just for us, presented by us and we just did and said what seemed right. The ballista was christened with wine, oil, wheat, blood and a popular nut based snack.

I don't know what I said, but it came from the heart. It was a very special occasion. The ballista was named Constantine, and I'm still getting used to that. The smell of incense, sweat, leather and iron gently made its way up the stairs and kept the public away. Then it was off to the pub!

Constantine was a great hit at the Festival of History. It was parked out in it's own little area having pictures taken of it's most intimate workings. Its portability was tested as we carried it to and from the arena, and its range was tested as we shot dramatically across the lake.

A few weeks later at Sewerby Hall Constantine was really tested each day. Dai Crawford took up the baton of ballistarius, and started destroying our targets. Then Constantine was covered in three types of oil, sheepskins and plastic to rest for the winter.

Subsequently, Dave Atkin and Mat Collins have specialised in the role of ballistarii, which demands a clear head and attention to detail, especially when members of the public lead their young family through two safety lines with warning notices to attempt to picnic hidden carefully behind the targets! Fortunately, quick command of 'State!' from the commentator was all that was needed and the weapon and range were promptly made safe.

They have also proven it possible to break the design down quickly into stand and engine, then carry a component each at the run to reposition, in the manner of a modern light machine gun team. Mat has pioneered an aiming system, practising on occasions into the night and shooting blind, enabling him to hit a man sized target with three shots out of three in displays, earning himself his character nickname 'Marcus Ters'.

We have continued to experiment with replacement arms and with bolts, varying length and heads according to different finds, such as the much longer bolts from Dura Europos.

Constantine alongside the classic earlier wooden framed design of the Legio II Augusta.

Long Dura style bolts top and bottom. A caged head for fire, plus socketed and tanged bodkin heads.