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Linear Obstacles - how do they work?

Posted: Fri Feb 04, 2011 8:03 pm
by SirGarnet
Obstacles are treated like Field Fortifications (see page 156-57). Undefended FF (or obstacles) do not impede movement sufficiently for the effect to be represented in the game. The front edge of the Obstacle (i.e., the other side) is "treated as the front edge of a battle group defending them" including for shooting ranges. So stepping up to a wide FF or Obstacle rather than a thin one means the zone of fire extends farther across the table from where your bases stand, and you can likewise be shot from farther away as you defend the position.

The above tells me that when no longer defending them, such as when you move off, forward or backward, the obstacle is treated as no longer there for movement purposes.

This also tells me that if a BG on either side routs when a BG is defending them , you measure the rout and the pursuit from the "front" edge that was being defended.

Break-offs require a little thought. Where you end in a break off is defined as a certain separation from your opponent, mounted a full normal move able to charge, and foot 4 MUs. Note that the attacker in contact with the defender edge of the Obstacle becomes the defender once the original defender breaks off, and as the new defender its front edge is treated as being the far edge of the obstacle. So, to achieve the necessary separation from the opponent, whichever side breaks off measures its break-off from its own side of the obstacle (which is at the moment now the defended edge) rather than the physical position of the enemy bases. The width of the obstacle obviously makes a difference here as to where on the table the troops end up, which could cut either way.

If there is a BG in the Obstacle area rather than defending it, the normal rules for open ground apply. It is treated as where it is. On the table it can then look odd that shooting can reach a BG as it sits defending an obstacle but can't do so when it moves 1 MU forward into the obstacle area. We need to remember that defending may mean taking up defensive positions ahead of the physical location of the bases.

From a visual and representational point of view, and a reminder to all, I would suggest that troops defending an obstacle, or at least their first rank, be moved up to the front edge of the obstacle while defending it.

This is analogous to the helpful practice (not in the rules) of files of a foot BG that are not themselves part of those giving rear support to artillery to be moved up level with the guns as a reminder that they are treated for all purposes as being in that position.

There may be some game advantages to wide obstacles, but the difference (in 15mm scale) between a minimum (15mm) and maximum (40mm) width Obstacle is only 1 MU, so not a big deal in practice.

Any corrections or thoughts?

Posted: Fri Feb 04, 2011 8:36 pm
by timmy1
Oh yes it is a big difference in 15mm.

While what you write is interesting I don't know that that is what the rules say.

'This also tells me that if a BG on either side routs when a BG is defending them , you measure the rout and the pursuit from the "front" edge that was being defended.
'

Not how the rules read if you turn round to face away I believe.

Posted: Fri Feb 04, 2011 9:00 pm
by SirGarnet
timmy1 wrote:Not how the rules read if you turn round to face away I believe.
Can you explain? Is this a comment re the edge and corner of the BG used for measuring the rout, or something substantive about where the BG rout is deemed to start its rout?

Posted: Fri Feb 04, 2011 9:07 pm
by timmy1
Not rout - you move away if you are going to be overwhelmed. Being more than 1 MU away has important benefits.

Posted: Fri Feb 04, 2011 9:30 pm
by SirGarnet
Yes, wide does give you a slight head start if your plan is to shoot and scoot. Also, a wide Obstacle means that enemy stopping at 1 MU and the defenders won't be in each other's restricted area (although they will be within charge range whether the Obstacle is wide or narrow). Dragoons will like the wide Obstacles so they can more nimbly sidestep or retire.

Do you see any of this as a game or balance problem?

Posted: Fri Feb 04, 2011 9:36 pm
by timmy1
Not a problem - I rather like it with Dragoons and LF. Seems historical. Given the' stop at 1 MU' you need the Obstacle to be more than 25.4 mm deep to not be in the restricted area. I believe that they should be limited to less than 1MU wide - same for FF. That prevents any problems.

Posted: Fri Feb 04, 2011 9:44 pm
by SirGarnet
timmy1 wrote: I believe that they should be limited to less than 1MU wide - same for FF. That prevents any problems.
But are there any specific problems with having it up to a base width wide, or can we call those tactical nuances? I think the flexibility in width is there to allow for different models (e.g., sunken roads modelled a base width wide) but the added tactical nuances probably encourage their use.

Posted: Fri Feb 04, 2011 10:16 pm
by timmy1
As a player who uses dragoons I know what I will choose...

Posted: Fri Feb 04, 2011 11:18 pm
by Blathergut
timmy1 wrote:Oh yes it is a big difference in 15mm.

While what you write is interesting I don't know that that is what the rules say.

'This also tells me that if a BG on either side routs when a BG is defending them , you measure the rout and the pursuit from the "front" edge that was being defended.
'

Not how the rules read if you turn round to face away I believe.

I would think that:

First: Routed BG turns and moves (measuring from new front edge)(former rear).
Second: Pursuers would measure as if in contact with them, so, if routers moved 3MU and pursuers moved 3MU, they'd end up in contact. In essence, the pursuers would gain that extra bit that was the width of the obstacle.

Yes? No?

Posted: Sat Feb 05, 2011 7:02 am
by SirGarnet
Blathergut wrote:
I would think that:

First: Routed BG turns and moves (measuring from new front edge)(former rear).
Second: Pursuers would measure as if in contact with them, so, if routers moved 3MU and pursuers moved 3MU, they'd end up in contact. In essence, the pursuers would gain that extra bit that was the width of the obstacle.

Yes? No?
I think No since I don't find anything supporting Yes, and Yes would be a bad game dynamic.

Note first that the situation of troops rear supporting artillery is comparable to those defending an Obstacle or FF. They are treated as having a front along the line of the artillery's front. They pursue broken enemy who were attacking the guns and fighting with the victorious troops from that position (p 131, col 1, last bullet) because that is their position per the rear support rules. So they also rout and are pursued from there. No one gets any bonus distance.

The game integrity problem with your suggestion in the Obstacle case is that it would make the total pursuit distance vary by the width of the Obstacle, which is gamey and not internally consistent. From the rules side, I don't see anything suggesting pursuers get a bonus - if they did, it woulid be on page 131 too. If routing defenders measured from their base position, they would have a head start equal to the width of the Obstacle.

The text treating the defenders as being at the front of the Obstacle is pretty clear to me (from which they would therefore rout and pursue, as in the rear supporting Artillery case). Neither pursuers nor routers gain or suffer from any extra move this way - the normal rout/pursuit dynamic and distance issues remain in place.

For that matter, the same concept applies to Portable Defences, except that in that case the troop bases are displaced back so the PD can be placed in front of them with the same overall front line as before.

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SPOILER:
Now, an interesting question is whether the differences in the front edge rule wording in these various cases have implications for inconsistent treatment of the rear edge (for things like being charged or shot at, or movement through that area).

Posted: Sat Feb 05, 2011 7:58 am
by hood_mick
I'm in an awful rush, so I may have miss read the above some what. But can I point out that you only have to stop 1 inch for a defended FF. So if a defending BG turns to bugger off, then you can infact charge it from over 1 inch away. So the being restricted or not due to fortificsation width doesn't realy matter so much.

Posted: Sat Feb 05, 2011 8:31 am
by timmy1
Mick, agree with your understanding other than I don't think the rules specifically state that you have to be facing a FF to defend it. (Somewhere) there is a bit about you can't count a flank or rear charge across a FF. It came up in my most recent game. I will see if I can dig it out.

Posted: Sat Feb 05, 2011 12:30 pm
by timmy1
Page 156.

'A base counts as defending field foritifcations if it is completely behind the fortification, with its EDGE touching the rear edge of the fortifications.' My emphasis on EDGE - note no mention of which edge. Also 'behind' is not defined. (Oh how lucky we are that Jer and Phil don't inhabit this realm...)

Page 157.

'The front edge of a FF is treated as the front edge of a battle group defending them, including for measuring shooting ranges.' Please note no mention of for measuring movement.

'Troops defending FF cannot be charged in the flank/rear across the fortifications.'

This all seems to apply to Obstacles as well. Those of a nervous disposition may wish to hold their noses at this point.

You choose an obstacle just over 1 MU wide. You station a Light BG along it facing the FF. Your opponent advances to 1MU away. You turn 180 degrees and move away. He can't charge you and count it as a rear charge. You are outside his restricted area while he is still 1MU infront of the Obstacle as you are more than 2 MU away. Holds up the enemy.

If FF and Obs are limited to less than 1 MU wide, this is eliminated.

Posted: Sat Feb 05, 2011 12:43 pm
by SirGarnet
timmy1 wrote:My emphasis on EDGE - note no mention of which edge.


Still, and perhaps because . . .
'The front edge of a FF is treated as the front edge of a battle group defending them, including for measuring shooting ranges.'
Please note no mention of for measuring.
Huh? Some words may be missing here.
timmy1 wrote:You choose an obstacle just over 1 MU wide. You station a Light BG along it facing the FF. Your opponent advances to 1MU away. You turn 180 degrees and move away. He can't charge you and count it as a rear charge. You are outside his restricted area while he is still 1MU infront of the Obstacle as you are more than 2 MU away. Holds up the enemy.
if you move away you are not in edge contact so not longer defending, and if in charge range you can be charged, right? Only as lights you could easily get out of charge range wherever you measure from and whether the Obstacle be 15mm or 40mm wide.

Defending and then abandoning the Obstacle or FF does slow the enemy as he prepares to assault the position, but that seems to me like what the Dragoons should be doing (unless they wish to actually come to blows, or exchange of fire).

Posted: Sat Feb 05, 2011 12:52 pm
by timmy1
Mike

Agree only works for lights as they are the only troops that can turn and move in the same turn. They key things is being more than 2 MU away from the enemy when you start the move, so not caught in the restricted area, they can then whiz off to the side with a wheel. Inside 2 MU and they are restricted, as I read it.

Sorry 'Please note no mention of for measuring' should read 'Please note no mention of for measuring movement'. I will go back and edit.

Agree that it is a historical tactic for the lights, especially the dragoons but I don't believe the authors intended the behaviour to differ depending upon the depth of the obstacle. Maybe I am wrong.

Posted: Sat Feb 05, 2011 2:09 pm
by Blathergut
Thanks for helping to sort this all out!

I don't think I'd be too hung up about the extra movement gain when a BG turns and moves away. Look at it as the other guys approaching have to get in/on/over/through more junk than the ones scooting away.

Posted: Sun Feb 06, 2011 2:51 pm
by rbodleyscott
MikeK wrote:
timmy1 wrote:My emphasis on EDGE - note no mention of which edge.


Still, and perhaps because . . .
'The front edge of a FF is treated as the front edge of a battle group defending them, including for measuring shooting ranges.'
Actually no. The reason that there is no mention is made of which edge is that a BG is intended to count as defending fortifications if its side edge is touching them.

A single FF section turned back 90 degree at the ends of a line of fortification thus protects the flanks of the BGs lining the main fortification.

Not only that but it would also protect the flanks of foot rear supporting guns lining the fortification, as they count "for all purposes" as if level with the front edge of the guns.

Posted: Sun Feb 06, 2011 8:12 pm
by timmy1
Richard

Agree that what you write is sensible but RAW do provide that the defending fortifications effects apply no matter which why the defenders are facing. Maybe a clarification is required (and no I don't want to suggest the words as it could end up being more complex than the rear support rule). :)

unless of course I have misunderstood your post, in which case please accept my apology.

Regards
Tim

Posted: Mon Feb 07, 2011 11:00 am
by rbodleyscott
timmy1 wrote:Richard

Agree that what you write is sensible but RAW do provide that the defending fortifications effects apply no matter which way the defenders are facing.
That is correct. If, for example, you have an enclosed fortification, then you would need it to work for the flanks and rear of the BG(s) inside.
unless of course I have misunderstood your post, in which case please accept my apology.
Apology accepted. :wink: