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Field Artillery - P. Clodius Secundus - 07-20-2007
Greetings Everyone,
Although there are a number of active artillery threads, I'd like to devote this one specifically to mobile field weapons. For those unfamiliar with the distinction between field artillery and siege artillery, the difference is mobility. Siege weapons are designed primarily for use in static situations defending or assaulting fortifications. Although they can and often were transported in wagons and carts, they usually require extensive set-up and emplacement before use. Conversely, field weapons are designed for rapid deployment in support of front line troops involved in offensive operations. In either role, one of the most useful weapons appears to have been the three-span catapult. Firing 2-3 foot iron-tipped bolts there are numerous references to them as "terror weapons". Up until about 100AD these weapons followed an evolutionary progression from their Hellenistic roots. These wooden-framed machines are well understood thanks to surviving manuscripts and modern research. Sometime around the reign of Emperor Trajan that class of weapon was radically redesigned. Most noticeably iron replaced much of the wooden frame work, but tactics seem to have been overhauled as well. What could have caused such rapid change?
To help the discussion I'd like to start by defining a few terms which are important to this topic. Feel free to add or improve definitions.
Catapult- also, engine, ferro-ballista, weapon, ballista, unless otherwise specified (manuballista, stone-thrower, etc) will be assumed to mean an
iron-framed machine capable of throwing a three-span projectile.
Carrus- a two wheeled cart, usually horse or mule drawn.
Vitruvian- Wood-framed weapon of the classical pattern which roughly conforms to traditional formulas.
Trajan's- The reliefs carved on Trajan's Column, particularly those which depict catapults.
Stand- also, monopod, base, tripod, column, all refer to the framework which supports and steadies the weapon.
Carroballista- A catapult and stand designed to be transported and shot from the bed of a cart.
It is my contention that the metal-framed catapult is an entirely re-designed weapon, literally from the ground up. Vitruvius' elaborate formula regarding the proper dimensions of the stand is void when discussing the carroballista. The basic form is still a single column or monopod design, but the height, ground base, and stay are by necessity different. At Roman Days Maryland this year I was able to try shooting Legio XXIV's catapulta from the bed of my reconstructed carrus. Since Gallio's existing base would not fit in the cart and neither would one built to Vitruvius's specifications, I used Trajan's as the inspiration for my design. Nearly everyone I spoke to cautioned me not to take my dimensions directly from Trajan's since "the perspective is off". Suspecting that a normal height would be hard to reach when cart mounted I made it shorter. Even then it was difficult to operate and we cut another eight inches off the stand. I intend to make one even shorter that very nearly duplicates the dimensions on Trajan's. In light of that affirmation of the artists I decided to take another look at the iconography. The two best side-view images I could find were The Cupid Gem and the Carroballista on the Column of Marcus Aurelius. When researching my carrus design Marcus Aurelius image had been helpful, but I hadn't seen how the incomplete framework it held resembled a ballista base. When I compared it to the Cupid Gem and applied the lessons learned Maryland it became obvious. A carroballista base is actually a truncated version of the Cupid Gem base. The lower half of the column is removed and the three legs of the ground base are replaced by a braced transverse beam as seen on Trajan's. The "stay" which normally is hinged mid-way up the column is now fixed near the head of the column and trails back at a roughly 30 degree angle and extends well beyond the horizontal plane. A horizontal brace is fitted between the transverse beam and the stay. When placed in the raised bed of the cart for shooting, the beam and brace lay flat on the cart bed and the stay hangs off the back just clear of the ground. The T-shaped base formed by the brace and beam is quite stable and the overhanging stay acts as counter balance so that no forward leg is needed. The hinged rest used to support the stock when winching and loading is no longer needed either. The stock can be braced directly against the stay. For transport the stay can be lifted and the base pushed forwards until the entire stand is on board. When shooting dismounted, the shortened column would cause the base to lean far forwards unless it were placed on a raised platform. Just such a platform can be seen on Trajan's. The one image of a catapult deployed away from the castra walls and its cart shows it with the transverse beam raised on a bed of log "cribbing". This roughly tri-pod arrangement would probably be quite stable. For the traditional mural defense role it could be placed on the parapet or a raised block just behind it. When pushed forward to the edge of the parapet it would make it easier for troops to pass by along the wall walk behind it and it would allow the shooter to sight further along the wall to either side. Both were drawbacks of Roman fortification design.
I have begun drawings of this design and will post them soon if anyone is interested. My existing base will soon be modified and field tested as well. Results and photos to follow.
Re: Field Artillery - D B Campbell - 07-20-2007
Quote:For those unfamiliar with the distinction between field artillery and siege artillery, the difference is mobility. Siege weapons are designed primarily for use in static situations defending or assaulting fortifications. Although they can and often were transported in wagons and carts, they usually require extensive set-up and emplacement before use. Conversely, field weapons are designed for rapid deployment in support of front line troops involved in offensive operations.Of course, the Romans had no such distinction. They simply called a catapult a catapult.
Quote:In either role, one of the most useful weapons appears to have been the three-span catapult. Firing 2-3 foot iron-tipped bolts there are numerous references to them as "terror weapons".Would you care to divulge these numerous references, Randi? :?
Quote:... but tactics seem to have been overhauled as well.Er ... how do we know this? We catch a glimpse of Caesar using the odd catapult in the field ca. 50 BC, then Arrian tells us where he'd recommend catapults to be deployed ca. AD 130. I can't think of anything in between. (Josephus describes what you would class as "siege artillery".) Have I forgotten something?
Quote:It is my contention that the metal-framed catapult is an entirely re-designed weapon, literally from the ground up.No-one will argue with that, Randi.
Quote:Vitruvius' elaborate formula regarding the proper dimensions of the stand is void when discussing the carroballista.Vitruvius doesn't actually describe the catapult stand. The tripod design that Schramm pioneered was based on Heron's description. Vitruvius does mention the ballista stand, but says only that it should be as high as necessary. There is no "elaborate formula".
Naturally, any description of a catapult stand cannot apply to a cart-mounted machine. Again, I don't think anyone would argue with that.
Quote:The two best side-view images I could find were The Cupid Gem and the Carroballista on the Column of Marcus Aurelius. When researching my carrus design Marcus Aurelius image had been helpful, but I hadn't seen how the incomplete framework it held resembled a ballista base.I presume you mean the peculiar cart illustrated in my [amazon]Greek and Roman Artillery 399 BC-AD 363[/amazon] (p.18 ) -- I think Alan (Wilkins) has a picture of it, too, but I can't remember where.
I wouldn't go so far as to claim that it's a carroballista. There is no sign of any torsion springs, for instance. It may just be a cart transporting a disassembled (regular) catapult.
Quote:For the traditional mural defense role it could be placed on the parapet or a raised block just behind it. When pushed forward to the edge of the parapet it would make it easier for troops to pass by along the wall walk behind it and it would allow the shooter to sight further along the wall to either side.There's no reason to suppose that "normal" catapults weren't used for traditional mural defence. To be honest, I wouldn't fancy being responsible for balancing an expensive torsion weapon on a parapet!
hock:
Re: Field Artillery - P. Clodius Secundus - 07-20-2007
Thanks for joining in Duncan. I knew you'd be here to keep me honest
Permit me to clarify my position on the points you raised.1. The modern distinction between field and siege artillery was included to give those joining us appoint of reference and to focus the discussion. The separate iron spring frames are referred to as kambestria (field frames) rather than the single capitula described in Vitruvius.
2. Some of the "Terror Weapon" references I alluded to can be found in the "Aitor Alert" thread. Again this was included as background for people just joining the discussion. I'm sure that those who mentioned those instances can better provide the sources.
3. I don't mean to imply that that field artillery supplanted siege weapons. It is the marriage of the three-span or equivalent to the cart that is signals the change in tactics. As far as there being nothing between Caesar and Arrian I point to Trajan's column as our best contemporary source. The seven catapults it depicts, considered in context, can be seen as an illustrated tactical primer.
4. The formula for catapult bases is from De architectura as described in the Wilkins JRMES article.
5. The cart on Marcus Aurelius had me puzzled as well until I concentrated not on what was missing but rather on the structural members that were there. Separating them from the structure of the cart brought to mind the Cupid Gem which predates it. It would appear that included in the picture are the column, stay, stock and an extended windlass box or bracket that secures the trail of the stock to the back of the stay. To counter your suggestion that the cart is being used for transport only, notice that the rear corner of the cart is cut off at an angle matching that of the stay. Our limited field trials have show that this would be a very practical modification. It gives the crew easier access and allows the stock a much greater range of traverse when elevated. I had thought of including it on my carrus, but since there was no depiction of it on Trajan's I left it out. I am planning to modify my cart to match this evidence.
6. Traditional "Vitruvian" weapons were used effectively for mural defense. In fact I would argue that until the advent of the carroballista that was their primary function. That doesn't mean that the new design didn't allow for improvements. As for your concern over placing a technologically expensive system on the edge of a wall, these are weapons not art installations. Besides, this would explain how the Hatra frame wound up face down with a broken slider. OOOps... :lol:
Re: Field Artillery - D B Campbell - 07-20-2007
Quote:Thanks for joining in Duncan. I knew you'd be here to keep me honest.
Well, Aitor hasn't taken the bait yet, so I thought I'd "step up"!
Quote:1. The separate iron spring frames are referred to as kambestria (field frames) rather than the single capitula described in Vitruvius.Indeed: Eric Marsden suggested that kambestria, an otherwise unknown Greek word, (1) was an abbreviated version of an otherwise unattested Latin phrase capitula campestria; and (2) it thus indicated "special spring-frames for field artillery as opposed to static engines" (1971, p. 222 n. 16). He may well be right. Nobody has made a better suggestion. (But it would be interesting to know what "static engines" Marsden had in mind.)
Quote:3. As far as there being nothing between Caesar and Arrian I point to Trajan's column as our best contemporary source. The seven catapults it depicts, considered in context, can be seen as an illustrated tactical primer.
You mentioned a change of tactics, Randi. As far as I can see, apart from the two cart-mounted machines, the catapults on Trajan's Column are being used exactly as Caesar (50 years earlier) or Arrian (30 years later) would use them.
I wonder why, if Trajan's cart-mounted machines ushered in a new set of tactics, they didn't carry over into Arrian's generation ?
Quote:4. The formula for catapult bases is from De architectura as described in the Wilkins JRMES article.Right. At De archit. 10.11.7, Vitruvius describes the (stone-projecting) ballista stand -- note that this is not the one that everyone uses for their arrow-shooters -- but he gives only the width and thickness of the column, not the height. That's the point I was making, Randi.
Quote:5. The cart on Marcus Aurelius had me puzzled as well until I concentrated not on what was missing but rather on the structural members that were there. Separating them from the structure of the cart brought to mind the Cupid Gem which predates it. It would appear that included in the picture are the column, stay, stock and an extended windlass box or bracket that secures the trail of the stock to the back of the stay. To counter your suggestion that the cart is being used for transport only, notice that the rear corner of the cart is cut off at an angle matching that of the stay.So that everyone (or anyone who cares !!) knows what we're talking about, here's the sculpture:
![[Image: Artillery_cart_small.jpg]](http://hometown.aol.co.uk/DBC633/Artillery_cart_small.jpg)
Again, we're pretty much in agreement -- the photo caption which I wrote in 2003 reads: "The wagon is carrying an object that resembles the catapult stand on the 'Cupid Gem'. It has been suggested that this is a disassembled artillery-piece".
However, I'm not convinced that the catapult is "combat-ready": there's no stock ("case"), and I definitely can't see any field-frames.
Quote:6. Traditional "Vitruvian" weapons were used effectively for mural defense. In fact I would argue that until the advent of the carroballista that was their primary function.I don't think we disagree on that, Randi. But the fact is: the carroballista is only mentioned by Vegetius. Nothing in Tacitus, nothing in Arrian, no sign of it in Ammianus or Zosimus. I just wonder if there was any change in tactics.
Re: Field Artillery - P. Clodius Secundus - 07-23-2007
Thanks for the clear photo of the cart from Marcus Aurelius. I've been working from a lousy one taken from a more direct angle. What I had interpreted as the overhanging end of the stay appears to be the upraised arm of a soldier below. It caused me to re-think things a bit, but in the end it actually clears things up a bit relative to Trajan's. I'd suggest that this one is in what could be called transport position. The case is there. It's the uppermost diagonal member. It attaches to the caput columellae at the top of the vertical column. Several things could explain the absence of the field frames. They could be removed during transport, they were broken off as were many other projecting details of the high-raised relief, or they were metal fixtures similar to those on Trajan's. Does anyone know if such existed on this column? (Notably, the carroballista on Trajan's that appears to be in transit forward to a field fortification has no slider evident. On the one being em-placed, the crew seems to be installing the slider).
It sounds like Marsden was making they same distinction based on mobility. I like his term "static" much better. I'll have to read his work.
The formula referenced for the stand is from Wilkins p.85. It includes dimensions for all major parts. He describes it as the basis for the Schramm, Morgan, and Feely three-span reproductions.
Since Aitor and the rest don't seem to want to join us, let me toss a little more fuel on the fire :twisted:
The other day I got to thinking about why they widened the frames. Longer string? Wider field of view?.... The Hatra find would seem to indicate that they could have done it in wood without even having full depth counter-stanchions.
Why switch to metal frames? Quick change-out to spares in the field?.... I've helped George Metz pull the double frame off his Vitruvian in less than the time it would take to unclip one field frame. Weight?.... If you're not designing it specifically for mobility, what's a couple pounds.
Why weaken the top fame by adding an arch?.... If it's just to clear the field of view, why not make it go down under the slider so you can just lay the projectile onto the projecting slider from above? You could hitch it to the front of the case to further stiffen the whole frame.
Looking at it from the front didn't seem to answer these questions so I took a walk around back to see it from the crew's perspective. The "shooter/winder" stands behind the case using his right hand to crank the winch. The "loader" (my favorite job on tanks BTW) stands to the left side using his right hand to push the slider back forward and lock the trigger pawls over the string. No need for the arch there. The string is even with the back of the frame....
Unless he has to reach an arms length forward of the frame to capture the bow string of an in-swinger. In that case an arch would sure make it easier to get his arm and seggie covered shoulder between the top frame and the slider. It's not proof positive, but with that in mind, the absence of such an arch would be pretty hard for the in-swingers to explain. At least it makes as much or more sense than "field-of-view". Make sure to tell the Grand Inquisitor that it's spelled Rand[/u]i .[u] :lol:
Re: Field Artillery - D B Campbell - 07-24-2007
Quote:The formula referenced for the stand is from Wilkins p.85. It includes dimensions for all major parts. He describes it as the basis for the Schramm, Morgan, and Feely three-span reproductions.Aha -- that's the stand which Heron describes. Schramm incorporated details from Philon to come up with the standard arrow-shooter stand that almost everyone uses.
I thought you were referring to Vitruvius' description of the stone-projecting ballista's stand, which is different (presumably because your average stone-projector would've been heavier than a 3-span arrow-shooter).
Quote:[Re. wide iron frame] The "loader" ... stands to the left side using his right hand to push the slider back forward and lock the trigger pawls over the string. No need for the arch there. The string is even with the back of the frame....Interesting idea, Randi. Dietwulf Baatz came up with the field-of-view reason for the arched strut. But, of course, the "inswinging" theory is anathema to him, so he wouldn't even have considered a slider that has to go so far forwards. But if the machine isn't an inswinger, as many people still maintain, then we're back at square one!
Re: Field Artillery - Nerva - 07-24-2007
Hmm, I'm not going to get dragged into this debate or I'll never stop. Anyway, we, the 'shamrock' Romans are constructing an Onager from Marsdens research. We will be fully documenting it's design and construction and will publish the results of our testing. This will all be up on our website, starting shortly.
The man doing the work is Sean Shiels, who has constructed medieval Trebuchett' in the past. Both Len Morgan and Tom Feely will also be involved as 'technical consultants' (sound good, doesn't it :wink: ) and with help from Len I hope to get some advice from Alan Wilkins.
We also intend making a two armed stone thrower or 5 span machine as well, but that will be sometime next year after we've got the onager out of the way.
while not the most elegant or common siege machine use by the Romans, it's far less complicated than the Carro or manu and will be much simpler and quicker to build and learn from. The initial idea is to have a machine capable of firing a 1kg (4.6 minae) stone. It will have a spring diameter of approx. 6.5", a length of 7', a width of 4' and a height of about 5'.
If anyone out there has ever built such an animal we love to hear from you.
Re: Field Artillery - D B Campbell - 07-24-2007
Quote:We also intend making a two armed stone thrower or 5 span machine as well, but that will be sometime next year.I take it you've still to decide between these two options.
(A 5-span is a hefty arrow-shooter designed for a 1.2m arrow -- similar to the 4-footer depicted in my [amazon]Greek and Roman Artillery 399 BC-AD 363[/amazon] plate B --, whereas a two-armed stone-thrower is designed to ... throw stones.
)
Re: Field Artillery - P. Clodius Secundus - 07-24-2007
Quote:[Re. wide iron frame] The "loader" ... stands to the left side using his right hand to push the slider back forward and lock the trigger pawls over the string. No need for the arch there. The string is even with the back of the frame....Interesting idea, Randi. Dietwulf Baatz came up with the field-of-view reason for the arched strut. But, of course, the "inswinging" theory is anathema to him, so he wouldn't even have considered a slider that has to go so far forwards. But if the machine isn't an inswinger, as many people still maintain, then we're back at square one![/quote]
Theories are like poor chicks... go ahead and persue 'em, but don't get married to one. :lol: I hope that any intellectualy honest person would glady consider alternative theories if only to feel more secure with his own. I'd love to see the performance numbers "crunched" objectively for best designs by both camps restricted to using exact copies of found frames (Orsova, Hatra, Sala et al) and Trajan's reliefs as guides. Knowing rather than assuming that in-swingers were either impractical, equal, or superior would allow the debate to focus solely on whether they did exist. One thing that bothers me is the rapid and radical nature of the changes that took place after the death of Vedinnius. It's almost as if the Vitruvian "ideals" were buried with him. In a sense they were, literally. It would really be interesting to see how the metal-framers would stack up to the older design. Unfortunately, even if it wound up being a "slam-dunk" one way or the other some folks would stamp their feet and pout
That's not really a bad thing in the end. New evidence or a new theory could always bring them back to the table. In the end the truth will out.
Re: Field Artillery - Nerva - 07-25-2007
A five span will throw stones as well with a change to the bow string.
Re: Field Artillery - D B Campbell - 07-25-2007
Quote:A five span will throw stones as well with a change to the bow string.... and a change to the design of the field frame!
For any non-artillerists reading this: a five-span is a euthytone catapult designed for an arrow of 5 spans in length (= 1.2m or c. 4 feet) -- hence the name. According to the formula preserved by Heron and Philon, a machine designed for this length of arrow has a diametros of 7 dactyls (13.5cm or 5¼"), which is basically the diameter of each torsion spring.
As a rule of thumb, a euthytone catapult (the Greek katapelta or Roman scorpio) can only shoot arrows, but a palintone catapult (i.e. a ballista) will shoot stones or (with some modification) arrows.
This is because the euthytone incorporates a grooved slider, which would be unsuitable for stones. In addition, it's one-piece frame has a rather narrow aperture for the missile: Vitruvius gives the dimension as "foraminis partis quartae" (= ¼ diametros). In a 5-span machine, the aperture would be a little over 3cm (1¼") wide; sufficient for an arrow, but unsuitable for a stone. However, the palintone's chelonium (the equivalent of the arrow-shooter's slider) is a generous 1¼ diametroi wide. (In a ballista with 7-dactyl springs, that's 16.9cm or 6½".)
In his introduction, Heron actually points out that, whereas euthytones can only shoot arrows, palintones can be used for arrows or stones. Clearly, besides replacing the bow-string with the "band" or "sling" of a stone-projector, a modified chelonium would be needed, with a different trigger mechanism and a more shallow groove appropriate for an arrow.
Re: Field Artillery - Nerva - 07-25-2007
Any piece of Roman artillery can fire a stone instead of a bolt with little modification. Granted, the ballistc performance would be totaly differient but there is no design or mechanical limitation other than the proprties of the projectile i.e trying to get a cheiroballistra to fire a 1 kg stone might be a bit of a problem.
Re: Field Artillery - D B Campbell - 07-26-2007
Quote:Any piece of Roman artillery can fire a stone instead of a bolt with little modification.... as long as it's a long, slender stone that fits on the slider and won't ricochet off the central stanchion.
Good luck with that!
Re: Field Artillery - Nerva - 07-26-2007
Actually D B, we're going to use 'guided rocks' specially built. Made from a laminate of sandstone, granite and limestone we will be able to change the flight path by illuminating differient parts of the stone with a heat ray - oh yes, the Romans had heat rays - the stone then expands or contracts thus changing the ballistic trajectory and allowing us to steer the stone to it's target.
There is clear evidence for this in the writing of Scientology!
We're examining the possibility of equiping eagles with the heat ray so they can guide to stone to remote targets. We hope to adapt the technology to bolts and have applied to George Bush for funding, we very much see this as a 'green' or 'organic' way of waging war :lol:
Re: Field Artillery - Robert - 07-26-2007
Good grief, Martinvs, I knew the Irish brewed some great whiskey but never contemplated the consequences :lol: