Visual Evidence for Roman Infantry Tactics

[Michael J. Taylor]

The publication of this project was sadly delayed due the illness of the editor, but might be of interest.  The article is part of a larger project on Roman military organization. Feedback welcome!

https://www.academia.edu/3394799/Visual_...ry_Tactics

[Steven James]

Like you, I also believe a unit was in open order by having every even numbered man in each rank move forward a few steps. The same principle I believe applies to a Macedonian phalanx. The concept by some scholars that an open order formation had double the frontage of a close order formation, to me lacks common sense and practicality. One such scholar shows how this works in his Osprey but his example only covers one unit, which would be easy enough to conduct. I believe what he has shown in a unit extending its frontage, and not going from close order to open order.

[Michael J. Taylor]

Yes, I think the transition to spacing must have been a pretty common dynamic in any infantry formation organized around shields. I do think that the basic logic of the Macedonian phalanx was quite different. The Macedonians seem to have had three orders--6 feet for marching, three feet on the offensive and 1.5 feet in a defensive. Asclepiodotus, whose Tactica is largely an exercise in mathematics, thinks that formations expanded or contracted laterally to achieve these spacings. So to does Polybius, but his own critique of Callisthenes suggests that it is Polybius who is wrong: when Polybius reports Alexander transitioning his formation from 32 to 16 to 8 before the Battle of Issus, his frontage is staying the same, he is simply collapsing down his files.
Still, from my own reconstruction based on literary and visual evidence, the Romans had only two basic formations, compared to the three Macedonian configuration: closed (testudo, synaspismos, etc.) and open (soluere ordines). I presume also that collapsing a deep formation was also more cumbersome, at 16-32 men deep, where as Roman ranks were much more shallow (10 seems to have been unusually deep). Thus a Roman century or maniple could flit between closed and open order, where it would have been more of a process to expand or contract a phalangeal formation, especially in the heat of combat when seconds count and even simple tasks become difficult.

[Bryan]

There are multiple ways of doing everything and I don't think there was ever only one way of doing something. For instance while having odd men in the first rank step forward (has to be odd, starting with the first man on the right, number 1, likely the centurion), an even easier way to go from close order (3 feet per man) to open order (6 feet per man), in the manner described in the texts in Michael's article when under missile threat, is for the maniple to charge out and out, so the frontage would fan outward as they moved, all ordered by a simple command to attack (having already been placed in close order, stationary or advancing). Using this method a unit can maintain its predesignated frontage (based on the width of the battleline, allowing it to fight in close and open order, going back and forth. Its weakness is that it requires dressed and organized rank and file, and that in the chaos of battle there is a chance that if and when the call to open order comes the men might not remember whether they are odd or even, or that the formation has collapsed a bit to the drill maneuver harder.  

I think a key reasoning behind the popularity of the concept of doubling the frontage of a unit by going from close to open order would be to close those nasty gaps which so many complain about. Skirmishers, whether velites or later auxiliary skirmishers, as well as armed servants (calones), would have filled the gaps to use missiles to prevent enemy penetration (which would be nearly suicidal for an enemy phalanx to try). But having a quincunx/checkerboard battleline, with maniple sized gaps, while actually engaged in combat is still unsettling to many and the remedy is that the maniples have originally been in roughly close order and then going to open order shortly before reaching the enemy during the advance (maybe even as part of the call for "Attack"). The skirmishers would already be pulling back at this point, to place themselves in the now smaller gaps, while the line infantry goes to open order and ensure ranks are properly distanced from one another (Polybius and Vegetius' 6 feet) so everyone is unimpeded while throwing pila. This is not complicated at all, it literally can be done with one voice or instrumental signal (preplanned), the interval between men in a rank doesn't even have to be exact, it can be a best guess of a shield's width between men in the rank or the first rank would extend to the left with shield arm parallel, umbo pushing against their left mate's shoulder, pushing the whole rank to the left, closing the maniple's gap. The other ranks in the maniple just cover down on the men who were previously in front of them.   

Does a battle line need to close its gaps all the time? I don't think so, even Caesar mentions at Pharsalus two under strength legions being placed so close to one another to make them appear as one unit, which implies that normally there was a distinct interval marking off each legion's "battlespace." I think partly the issue of gap vs no gap depends on the terrain, while many imagine pitched battles mostly happening in big open, grassy plains, the reality is that oftentimes battles would be fought in wooded areas, lots of impeding brush, stream beds, hillocks, clefts, demarkation hedges and stone walls or wooden fences for farming plots, and other terrain features and microterrain that would make dressed lines and close interval marching problematic to the say the least. Then comes the adversary dictating the size of gaps. I think facing an enemy who has a heavy missile advantage means close ranks are necessary but gaps are usually safe. While fighting against enemy who posses line infantry (I really don't like calling them heavy infantry) formed in a phalanx/shield wall would mean that gaps in the Roman line are fine and open order for close combat is a must. But Romans fighting other Romans, or enemy infantry who are capable of operating independently in smaller units and not in an unbreaking shield wall/phalanx, then I believe that maniples should fight in open order but that the gaps between maniples and legions would be either removed (2nd line maniples covering down maybe?) or at least shortened through my previously mentioned open order, extend frontage maneuver.

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So to does Polybius, but his own critique of Callisthenes suggests that it is Polybius who is wrong: when Polybius reports Alexander transitioning his formation from 32 to 16 to 8 before the Battle of Issus, his frontage is staying the same, he is simply collapsing down his files.

Can you elaborate on this?

[Nathan Ross]

the Romans had only two basic formations...: closed (testudo, synaspismos, etc.) and open (soluere ordines).

Probably, yes, although I think the testudo was a particular (third?) formation used principally for attacking fortified positions. The same word seems to be used in the later empire for the defensive 'shield wall', which perhaps later became known as the 'fulcum'. There's also the formation which Ammianus calls the 'praetorian camp', which seems to be closer still, perhaps, or just deeper.

The 'closed' formation of the republic and principiate might be better called something else - both Tacitus and Livy use frequens ordinibus for a 'close order' array, from which troops could attack in the cuneus.

I'm not sure if the Trajan's Column relief you use in the paper represents a battle formation - the troops seem to be bodyguards protecting the emperor's cart - although it may well have appeared roughly the same!

Maybe the Glanum stela depicts something like a 'close order' formation? The legionaries are shown holding their swords, in close rank - perhaps an advance into battle, or a pre-battle parade?

[Rod MacArthur]

Speaking as a former British Army officer, the logic of changing quickly from open order to close order, by alternate ranks stepping forwards or backwards, makes perfect sense. By this logic a Century of 80 men in open order would be in 8 ranks of 10 files (at 6 feet per file). By the alternate ranks stepping forward they would instantly be in close order of 4 ranks in 20 files (at 3 feet per file) with exactly the same frontage in open and close order.

Assuming they were operating in two Century Maniples, then if it was desired to create a close order formation of 8 ranks, the Posterior Century could simply be closed up to the Prior Century. Provided the overall array was in a chequerboard formation then gaps between Maniples could simply be closed by bringing forward Maniples from the second row, not by doubling the frontage of each Prior Century.

Rod

[Renatus]

The soldiers are holding the hilts of their swords but the swords are sheathed. However, what interests me is the soldier on the right. All the others are holding their shields so that we see the right-hand side of them. He seems to be showing the left-hand side of his shield. Why is he doing this? It looks very awkward to me.

[Bryan]

The soldiers are holding the hilts of their swords but the swords are sheathed. However, what interests me is the soldier on the right. All the others are holding their shields so that we see the right-hand side of them. He seems to be showing the left-hand side of his shield. Why is he doing this? It looks very awkward to me.

Good eyes. I'd guess the sculptor screwed up.