Mounted 1H Retreat and Interpenetration

A mounted unit that ends a round of melee with Foot can voluntarily retreat 1H. The question from a recent game was whether the "retreat" is voluntary or involuntary. The implication is around how interpenetration works in those situations.

This is the original situation. The CM and FP ended the round in a draw.



The CM wanted to retreat 1H back on top of the CL.



Question, what happens to the CL? Does it displace the CL forward? Does it push the CL back? Does the CM go through the CL to the far side? I'd be interested in what others think.

I think the following snippets cover the options

Rules wrote:7.7.2 Loss of Melee and Retreat of the defeated Unit
However Mounted Units that end the melee with Foot in a draw may retreat 1H if they want to do so.

If the retreating Unit meets friendly troops then see par. 5.11.2

Hard to read that as anything other than voluntary - its not a forced action, you get to choose but are referred to 5.11.2 which is Forced Moves and Interpenetration, odd!

Rules wrote:5.11.2 Forced Moves and Interpenetration
When a Unit is forced into contact with another friendly Unit due to a pursuit or a retreat after a melee (not evasion as it is a voluntary move):

b) If retreating, it can interpenetrate any Unit (even if move distance remaining is not enough) if the interpenetration is allowed according to par. 5.11.1,

Ok that says you can do it if allowed under 5.11.1 - its odd as its not really forced but we seem to end up at voluntary anyway.

Rules wrote:5.11.1 Voluntary Interpenetration
When S, T, FL and CL are interpenetrated, these automatically allow the interpenetration, moving behind the interpenetrating Unit after the movement is completed.

The interpenetrated Unit can be forced to move forward and perhaps closer to the enemy when the interpenetrating Unit approaches it from the front and doesn’t have enough movement left to pass completely through

So the CL allow the interpenetration. "moving behind" is typical weird impetus speak but I think we all agree that it means the CL is not pushed back but slides forward if needed. In order to make room for the interpenetrating unit.

The second para seems to confirm the intent that the CL can end up closer to enemy.

So I think The CM retreat 1H, partly interpenetrating the CL, who as a result are nudged closer to the enemy. I can see that as the formed body moving back and the lights circling round protecting and shielding by harassing the enemy. In the end the CL don't care so much as they can evade any aggression to take station behind the CM again.

Great analysis Zippee, that is how I would play it.

Thanks Zippee for the detailed response. I personally am uncertain if the 1H retreat is voluntary or involuntary. The way it is written it could be either in my opinion. Assuming that you are correct, however, one option I didn't include was the CL simply displacing behind the CM.

On pg. 32 it says, "When S, T, FL or CL are interpenetrated , these automatically allow the interpenetration, moving behind the interpenetrating Unit after the movement is complete." That would seem to mean in the above example the CL displaces backwards.

If, in fact the CL displaces forward as you suggest what does one do in the situation where there is not enough space available for the CL to do so. Does that prohibit the CM from retreating or do we move the CM back further to allow space for the CL.  

I find the rules around interpenetration challenging to decipher in Impetus 2 (and also in Impetus 1!)

7.7.2 wrote:if they want to do so

How can that be anything other than voluntary? If someone forces me to walk out the door I'm NOT doing it because I want to, I'm doing it because I HAVE to - force removes choice, that's why force is used.

I may want to do so because staying where I am is dangerous but the choice is mine - the enemy haven't forced me to do anything, I'm choosing to do so, no matter that the reason is one of face saving …

Of course its always possible 'want' isn't the word that was wanted !!

Yes that is 5.11.1 which I quoted and I commented on it being odd wording above. Its also why I included the next paragraph, I think that confirms the intent that the CL will often be required to move closer to the enemy because of the interpenetration.

Discussing 5.11.1 & 5.11.2 may be worthwhile as I agree the intent is obfuscated by the words but I don't think that's specific to the question of CM choosing to retreat from a drawn combat. So lets park that for a different thread as interpretation here has a much wider impact than this question.

I haven't worked through every possible geometry but I'd expect that if there was room for the CM to exist in front of the CL, there should usually be room for the CL to move forward. So not sure how often it would crop up but I guess it could …

If there isn't room to execute the manoeuvre, I'm pretty sure the standard rule is that you can't do the manoeuvre. So I'd expect that to be the case here - the CM would dearly like to pull back but the CL have got all excited and closed up too tight and there just isn't enough space to safely undertake what is a fairly complex manoeuvre.

I'd blame the commander - crucifixion is probably the best solution

The reason I am not completely convinced by your reasoning Zippee is because the 1H withdrawal is called a "retreat" (ie. "may retreat") and the voluntary nature is not the retreat itself but whether to do so. A retreat is, by nature in Impetus, a forced move. If the phrase "1H withdrawal" had been used then I would completely and whole heartedly agree with you. I am not disagreeing either with you (and others in my group concur with you) but I would like some clarification on the issue.

With that being said, it seems we have two options now.

CL displace forward (if space is available.)
CL displace backwards.

Since a mounted base in 28mm is 8cm in depth and 1H is 6cm if there is a CL immediately behind (or at least close enough to be backed on to by) the CM in the above example there will never be enough space for it to be displace forward.

The phrase "if they want to do so" in 7.7.2 has to mean something. I don't see it as making the retreat mandatory. I notice that the rules sometimes use the phrase "forced to retreat." If retreats are always mandatory, why also used the word "forced?"

Does anyone have a copy of the Italian version of the rules to compare it to the English version?

Ok but I don't actually think it matters.

7.7.2 refers us to 5.11.2 if the retreat meets a friendly unit. It's irrelevant at this juncture whether we consider it voluntary or forced narratively. The rules refer us to the forced interpenetration rules.

Rules wrote:5.11.2 Forced Moves and Interpenetration
When a Unit is forced into contact with another friendly Unit due to a pursuit or a retreat after a melee (not evasion as it is a voluntary move):
a) If pursuing, it will interpenetrate the friendly Unit if allowed to, according to par. 5.11.1. If not, it will stop on contacting the friendly Unit
b) If retreating, it can interpenetrate any Unit (even if move distance remaining is not enough) if the interpenetration is allowed according to par. 5.11.1, or if the retreating Unit is CL, T and FL (not impetuous). Otherwise, it can or must (if interpenetration is not allowed) push back straight, with no sideways movement) and disorder (if not already disordered) any friendly Unit it meets. Wagenburgs cannot be pushed back. An interpenetrated Unit cannot be moved into contact with enemy under any circumstances.

So let's parse that out: line one merely asks if the potential interpenetration is caused by pursuit or retreat.

option a is pursuit - your CM are not pursuing, we can safely disregard section a.

option b is retreat - this is what we need to read:

5.11.2 b wrote:it can interpenetrate any Unit (even if move distance remaining is not enough) if the interpenetration is allowed according to par. 5.11.1, or if the retreating Unit is CL, T and FL (not impetuous).

So your CM can interpenetrate the CL if it's allowed under 5.11.1 which are the voluntary interpenetration rules.

It can do so

even if move distance remaining is not enough

Not enough to do what? Who knows but whatever it is we can do it! Probably not enough to clear the unit but that'd be a guess. We're CM so the CL, T, FL impetuous clause is irrelevant.

Next line tells what to do if the line above isn't true. as 5.11.1 will tell us we can interpenetrate, this also is irrelevant,

The last line is also irrelevant, no wagenburgs and no enemy contact to stop us.

So onto 5.11.1 which is voluntary interpenetration. So regardless of whether choosing to retreat is mechanically a Forced Move or a Voluntary Move we end up following the Voluntary Move rules.

The first 4 clauses of 5.11.1 tell us whether we can interpenetrate. Clause 4 confirms that we can

4 wrote:Light Cavalry can interpenetrate and be interpenetrated by any Mounted with exception of Elephants.

CM through CL, that's us.

Next we have para 1 of a text block

When S, T, FL and CL are interpenetrated, these automatically
allow the interpenetration, moving behind the
interpenetrating Unit after the movement is completed.

ok that applies - the CL allow the CM through and "move behind" them after movement is completed. Behind not in front - if I expected the CL to be pushed in the direction of the interpenetration I'd say they were pushed, placing behind must mean behind the CM's path of movement. It's tricky wording because it could be talking about the facing of the CM not its movement path.

(I'm skipping the next two paragraphs deliberately, I'll return to them at the end but para 2 refers to other units and large units so doesn't apply and para 3 allows for an unusual situation. They don't affect us, para 1 is what we need to follow).

We then get the ABC of dealing with interpenetration. A is important to us and confirms that the interpenetrated unit can end up closer to the enemy.

A) The interpenetrated Unit can be forced to move forward and perhaps closer to the enemy when the interpenetrating Unit approaches it from the front and doesn’t have enough movement left to pass completely through the Unit it is interpenetrating.

For me this confirms "move behind" but I accept that forward could relate to the CL's facing - in your case that puts them closer to the enemy you retreated from. But equally enemy could be behind the CL so its not definitive.

B is concerned with side and rear interpenetration so irrelevant to your example.

C) In every case the interpenetrated Unit must keep its original facing and cannot move sideways.

applies but doesn't help with where you move the CL

Nowhere in that is there a clear suggestion that the CL displace backwards away from the CM. All we have is "moved behind" and in context I have to read that as behind the CM after you've moved it - displaced closer to the enemy as the next paragraph clearly warns us is a likely consequence. And I feel it wouldn't warn us of this if the CL were to be pushed ahead of the CM - in such a case that would be 'away from the enemy' not 'closer to the enemy' in any but a peculiar situation.

Placing the CL behind the CM, closer to the enemy unit the CM retreated away from is always going to result in the CL being moved closer to enemy and makes sense of that warning being included.

I fully agree that it's not crystal clear but I feel that's the simplest reading.

Finally, the space issue and paragraphs 2 and 3 i skipped earlier. I think paragraph three may cover us

The exception is when the interpenetrating Unit starts its movement in base to base contact with the Unit it wants to interpenetrate. In this case the interpenetration is allowed even with one move action, allowing the crossing Unit to move more than normal.

Now, does this apply to all interpenetrations or just the "other units and large units" of paragraph 2 - unclear because its paragraphs not a bullet list but it would allow the CM to clear a CL if in contact.

It still leaves the issue of if the CL are 2mm behind, then you're stuck. But either you grasp the straw of paragraph 3 applying and retreat or adopt the "if you can't complete it you can't start it" ruling.

If I was to request clarity from da boss it would be to clear up what is meant by:

5.11.1 moving behind the interpenetrating Unit

and

5.11.2 even if move distance remaining is not enough

the rest I think is clear enough

Zippee, I think you are correct about voluntary or involuntary nature of the "retreat" is irrelevant in this case. This might be a holdover in concept on my part from Impetus 1. It doesn't seem to matter anymore.

The more normal path of movement in Impetus is a CM moving forward and sitting on top of the CL displacing the CL backwards behind it. In this case the CM is moving backwards on top of the CL. The question for me is does the direction of movement effect the displacement? The bottom of p.32 would seem to suggest yes but not sure.

As far as placement goes, since the depths of units are exaggerated in gaming I'd be open to fitting in the units so that it can work.

The concept of Voluntary or Forced is still there but it seems we determine which mechanism to use by working through 5.11.2 rather than by having a list of this is that and that is the other. And in reality Forced isn't interpenetration at all.

That's what I was meaning by does 'move behind' reflect the facing or the movement of the unit. I'm not sure that interpenetrating forward is commonly more frequent than retreating backward but I'm pretty happy in my understanding that 'move behind' refers to 'from where the unit came' and not 'to its rear'.

The only time "pushed back" is used is in the context of the interpenetration not being allowed under 5.11.1.

5.11.2 wrote:Otherwise
it can or must (if interpenetration is not allowed) push
back (straight, with no sideways movement) and disorder (if not already disordered) any friendly Unit it meets.

So in a broad sense, Voluntary allows interpenetration and the unit moves through and displaces the interpenetrated unit behind it. Whilst Forced disallows interpenetration and requires the unit to push back and disorder the other unit.

There are a three other statements in 7.7.2 that both help and add confusion - mainly by being text blocks so being unclear to what they apply:

Retreating Units cannot push back friendly Units that are engaged in a melee, nor can they push back enemy Units.

If the retreat cannot even start due to a friendly or enemy Unit that is blocking the path then the retreating Unit is destroyed.

If the retreat can start then there are no effects apart from the fact that the retreat is interrupted once the contact is made and if the melee continues and the Unit is forced to retreat again that Unit will not be able to start its movement hence it will be destroyed.

Para 1 and 2 presumably both only refer to enemy units or friendly units in melee. It's not 100% clear that's the case but I can't see any other way a retreat could be blocked.

Para 3 tells us that a retreat can stop short because of difficulties - again probably a blocking unit. But maybe it also applies if the requirements of displacement can't be met. Perhaps if there isn't room for the CL to reform behind the CM (and closer to the enemy) then the CM retreat until the meet the CL and stop.

Such nuance and exactitude only matters in competition gaming as far as I'm concerned. At my table I'd just look at the situation and do what felt right - if that means the CM retreat a few mm further than they really should then so be it.

I have read the Interpenetration rules over again several times and we chatted about it last Sunday evening Impetus night as a group.

The only differences that I can see between Voluntary and Involuntary Interpenetration are the following.

1. CL can interpenetrate Foot units in a forced move. That is not possible with a voluntary move (ie. CL could not evade behind FP but could retreat behind it.)

2. Similarly, FL and T can interpenetrate Mounted units in a forced retreat but cannot do so voluntarily. (This is an interesting feature of Impetus. Mounted units can interpenetrate FL/T voluntarily but FL/T cannot do the same in reverse.)

3. When formed units (ie. FP, CM, CP) are forced to retreat they push back other formed units. Formed units cannot push back other formed units during regular, voluntary moves (ie. a CM could not move backwards voluntarily if there was an FP behind it in the way but would push it back in a retreat.)

We've decided as a house rule that when units are displaced forward we will adjust the spacing to allow this to happen.

That's a great summary Gaius. It's easy to miss or forget note 2 (re: interpenetration as to FL and T).

you can choose to retreat or not.

If you retreat then follow this rule:

If retreating, it can interpenetrate any Unit (even if move distance remaining is not enough) if the interpenetration is allowed according to par. 5.11.1, or if the retreating Unit is CL, T and FL (not impetuous). Otherwise, it can or must (if interpenetration is not allowed) push back straight, with no sideways movement) and disorder (if not already disordered) any friendly Unit it meets

In the specific case CM can intepenetrate according to  5.11.1 so goes behind the CL. If there is no room CL moves foward for the necessary to allow the interpenetration.