Instances and Interpretations of Interpenetration

[Chris]

Gentlemen,

Interested in finding out more about friendly unit interpenetration and was wondering if those with greater knowledge (that would include everybody else) had any ideas about where to look and who to read.

Guessing that it did happen historically, as many rulebooks contain sections on interpenetration.

Thanks.
Cheers,
Chris

[Jim Webster]

Gentlemen,

Interested in finding out more about friendly unit interpenetration and was wondering if those with greater knowledge (that would include everybody else) had any ideas about where to look and who to read.

Guessing that it did happen historically, as many rulebooks contain sections on interpenetration.

Thanks.
Cheers,
Chris

I think we know that light infantry could fall back through the main line of heavy infantry, but I doubt anybody has evidence of a mechanism
We also have evidence of interpenetration in later periods
Wargamers need it for game purposes 

[Mark G]

Take your game scale into account.

I would expect none of your example other rules model every maniple .

But they have a list of mid republican romans.

And they decided to allow some form of line replacement between hastatii principes and triarii, without explicitly declaring whether they believe the lines form a continuous front, or retain maniple spaces along the front, and thus how that would happen .

And they get around this by allowing interpretation.

Now you need to go back, and decide whether you do want to see the individual maniples modelled, do have a strong view on how they operated, and therefore can make a rule to cover that activity on the table. 

Or, you can not ask this question, and just accept it's a rule fudge for a difficult question.

Ditto English billmen and archers.

Pointless looking at later examples, because they had strict drill, cadence marching, etc.
And besides, opinions there are pretty divided too.

[Erpingham]

Wargamers need it for game purposes 

Or we assume it happened but don't know how, so abstract it.

Add: Crossed with Mark's post.  Scale is key.  Lines interpenetrating lines is a different scale to troops moving through the ranks of a unit.  Often we do not know, because it presumably wasn't important, whether troops moved through the ranks or funnelled round the sides of units.  The effect would be the same. 

[Justin Swanton]

Onasander describes the interpenetration mechanism for light infantry passing through heavy infantry in a military treatise destined for Quintus Veranius Nepos, consul in 49AD and Legate of Britain. It applies to Hellenistic-style skirmishers like slingers and archers withdrawing through a phalanx of heavy foot, but the mechanism would be familiar (and relevant) to a Roman general like Nepos.

There should be intervals [διαστήματα - diastemata, which means 'gaps' in this context] within the ranks [κατὰ τὰς τάξεις - kata tas taxeis; in this context kata means 'throughout'; taxeis in the plural applied to a single phalanx line means 'ranks'], so that, when the light-armed troops have discharged their weapons while the enemy is still advancing, before the two armies come to close quarters, they may about-face, pass in good order through the centre of the phalanx, and come without confusion to the rear. For it is not safe for them to go around the whole army, encircling the flanks—since the enemy would quickly anticipate them in this manoeuvre, coming to close quarters and intercepting them on the way—nor is it safe for them to force their way through the closed ranks, where they would fall over the weapons and cause confusion in the lines, one man stumbling against another. - Strategikos: 19.1

In effect Onasander is describing the open order formation of the Tacticians, the latter of whom specify that this was the way of allowing one body of light or heavy infantry to be intercalced with another body of heavy infantry (Asklepiodotus: 5.1). It is easy to extrapolate an intercalced body of light infantry to that body advancing ahead of the body of heavy infantry it was part of in order to skirmish with the enemy and later withdrawing through the file gaps of the heavy infantry to evade the enemy advance.

[Andreas Johansson]

The Praecepta Militaria of Nicephorus Phocas describes cavalry and light foot moving in and out through the intervals between units in a heavy infantry line.

The work with translation, background, and commentary is available here.

[Erpingham]

The Praecepta Militaria of Nicephorus Phocas describes cavalry and light foot moving in and out through the intervals between units in a heavy infantry line.

The work with translation, background, and commentary is available here.

For an earlier work by McGeer, summarising the Praecepta, see this article The line gaps were wide enough for 12-15 cavalry at a time to ride through them.  They could be blocked by light infantry if the enemy threatened.  Light infantry could also move through them to outflank the enemy.

[Justin Swanton]

The Praecepta Militaria of Nicephorus Phocas describes cavalry and light foot moving in and out through the intervals between units in a heavy infantry line.

The work with translation, background, and commentary is available here.

The key words will be "intervals" and "between". Is there an online text of Phocas anywhere?

[Erpingham]

The Praecepta Militaria of Nicephorus Phocas describes cavalry and light foot moving in and out through the intervals between units in a heavy infantry line.

The work with translation, background, and commentary is available here.

The key words will be "intervals" and "between". Is there an online text of Phocas anywhere?

In the article mentioned, McGeer gives the word for interval as χωρια, if that is any help?

[Justin Swanton]

The Praecepta Militaria of Nicephorus Phocas describes cavalry and light foot moving in and out through the intervals between units in a heavy infantry line.

The work with translation, background, and commentary is available here.

In the article mentioned, McGeer gives the word for interval as χωρια, if that is any help?

The key words will be "intervals" and "between". Is there an online text of Phocas anywhere?

It does, but it would be nice to see the context.

[Andreas Johansson]

There doesn't seem to be an online version, no. (It seems that sources after about AD 500 are much less likely to be available online than later ones. Normally I'd blame this sort of thing on Disney, but here it's probably due to the traditional valorization of the classical over the medieval.)

Anyway, I'll transcribe a couple key sentences:

hê de toiautê parataxis tôn eirêmenôn pezôn estô tetragônos dittê, outô legomenê para tois palaiois tetrapleuros, ekhousa kath' ekastôn meros ana paratagas treis, ôs einai omou dia tôn tessarôn pleurôn paratagas dôdeka. einai de autas diakekhôrismenas hoson estin dynaton khôrein kath' ekaston khôrion kaballarious dekapente eite kai dôdeka tou eiserkhesthai kai exerkhesthai tous polemountas.

I hope this helps, because this is about the limit of my apetite for transcription. It's the first two sentence of ch.I §5.

[Chris]

Many thanks Magisters.  Much appreciated. Much food for thought here.

Cheers,
Chris

[RichT]

χωρια - same word as in the chapter heading of Onasander 19 (Loeb translation = "the phalanx should have intervals")

τὰς τάξεις - in the context, files not ranks (Loeb translation gives ranks, but comparison with Asclep 6.1 etc makes files more likely - taxeis can be used for pretty much anything).

[Patrick Waterson]

τὰς τάξεις - in the context, files not ranks (Loeb translation gives ranks, but comparison with Asclep 6.1 etc makes files more likely - taxeis can be used for pretty much anything).

Which makes diastemata kata tas taxeis more along the lines of gaps between files (as opposed to, say, between subunits).  Densing up for shock combat would thus have to occur after skirmishers have passed through friendly lines, which makes sense.  It also suggests that recalling your skirmishers when the other side does is a good idea because otherwise when his densed-up troops charge he will drive your skirmishers back through the gaps between your files and then crush your still-not-densed-up formation with his own fully-densed one, driving it back with disorder and loss.

The as-yet-unanswered question would seem to be whether the intervals are 6' intervals (one man per 6') or 3' intervals.  I would suggest 3' intervals (one man per 3') as this permits effortless passage of lightly-equipped humanity while leaving only one process to undertake to finish 'densing up' the phalanx to its most effective 18" individual spacing.

[RichT]

Well - given that Onasander was writing mid 1st C AD, a full century after the last Macedonian phalanx, and that his work (unlike Aelian/Arrian, which are overtly antiquarian) was intended to be of practical value, it's rather unlikely that he has any specific Hellenistic drill in mind, and more likely that he is using his reading (including of Hellenistic Taktika) to make a general observation about light and heavy infantry that would still be applicable to his Roman audience. So a vague translation (like the Loeb) probably well conveys what he had in mind:

"There should be gaps in the lines so that, when the light-armed troops..." etc.

But from a source criticism perspective, given that Onasander might well have been inspired in his comment by Hellenistic Taktika and that these (judging by Asclep. 6.1) refer to LI being interspersed among the files of the HI, something that Asclepiodotus (etc) calls 'parentaxis' (and note that that one of the manuscripts of Onasander has 'parataxeis' in place of 'tas taxeis'), then 'files' is probably what was originally meant and what inspired Onasander's comment. That said, to a Roman readership familiar with Roman deployment, it could just as well be read as:

"There should be gaps between the units so that, when the light-armed troops..." etc.

Onasander isn't specific as to which he means and it's probably quite deliberate that the phrase is ambiguous. Trying to extract precise tactical details (of what army? In what period?) from this is unwise.

Bottom line, post sledgehammer and nut, yes Onasander (and Asclep etc) do appear to provide examples of LI directly interpenetrating HI, though without details of exactly how (which as wargamers we can happily abstract away).