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Author Topic: Traps, bridges and moats  (Read 805 times)

telamon

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Traps, bridges and moats
« on: February 09, 2010, 05:18:14 pm »

I just dealt with the first kobold thief. My two war dogs took care of him pretty easily (I also drafted my weapon-wielding miners and woodcutter in case) but it got me thinking about my military preparations.
I intend to create a moat over which a drawbridge will control entrance to my fortress. However, not being willing to channel down (because much of my fortress is on the first z-level), I want to simply set up all my defenses one level in the air, using a mass of constructed walls. I have hundreds (450+) of chalk pieces lying around so materials are not an issue.
So first of all, how effective is a constructed moat? That is, I have a ring of walls, and the only way into the walls is by means of a drawbridge, which connects to a wall outside the ring. This wall has ramps for caravans. I'm trying to avoid digging a moat because, as I said, most of my fortress is on zlevel 1.
Second, can I place traps on a bridge? If not where should I put them? At the base of the outside wall, ahead of the bridge, or at the base of the inside wall, once someone steps off of the bridge? And will my traps obstruct caravans?
Should I construct a platform so that ballistae can fire down the bridge?
Finally, can I construct walls on the bridge so people don't fall off, or will I just have to live with that risk?
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jayseesee

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Re: Traps, bridges and moats
« Reply #1 on: February 09, 2010, 05:58:44 pm »

Alright, trying to decipher what you are saying.  Here's a picture for an idea

Code: [Select]
W = Wall
. = Floor
 = Open space
t = Trap
^ = Ramp up
V = ramp down
b = drawbridge, preferably retracting

Z - 0
This would be your level you want to raise over
   Moat
WWW   WWW
 ^W   W^
 ^W   W^
 ^W   W^   
WWW   WWW
   Moat

Z + 1
This would be the new level that you just made above the ground.
WWWWWWWWW
WVtbbbtVW
WVtbbbtVW
WVtbbbtVW
WWWWWWWWW

Pardon the terrible ascii, but see where I'm getting at?  Gives you traps, bridge for shutting it, and wagon access.  Just be careful designating it, and make sure you do the top level walls by one step in from the outside at a time, or else they will be considered unsupported and cave-in, if that makes sense.
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I'd do that, but I don't think dwarves have words for "fair" or "logical".

telamon

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Re: Traps, bridges and moats
« Reply #2 on: February 09, 2010, 06:29:36 pm »

I see. (You had my idea just about right) So although I couldn't place traps on the actual bridge, I could place them on the entry/exit points. I presume they don't block caravans, based on that ascii art.
And should I use retracting instead of drawbridge? What are the advantages/disadvantages? (Drawbridges can atomsmash, which I'd say is a major advantage.)
I kind of see what you're saying with the top-level walls. They're to prevent people from falling off the bridges, right?
And can I construct walls on top of walls? If so I suppose that'd work, thanks! (It gives me some nasty ideas of building fortifications over the bridge.... hehehehe... Wait, when you raise a drawbridge, does it occupy space in the sky?)
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Jacob/Lee

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Re: Traps, bridges and moats
« Reply #3 on: February 09, 2010, 06:33:36 pm »

Traps don't block wagons.

You can use retracting bridges to dump unwanted hostiles/stuff/nobles in a hole.

And you can put walls on walls as long you don't put floors on it first.

telamon

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Re: Traps, bridges and moats
« Reply #4 on: February 09, 2010, 06:36:41 pm »

True but I'm not going to have an actual hole, just a gap between two walls. (I could just cover it with tons of traps or spikes and make walls around it so it would actually be a hole, though. I suppose that would be worth it. Is the bridge going to retract fast enough that enemies on one end will fall by the time it pulls back, with a length of about 5-7 spaces?)
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jayseesee

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Re: Traps, bridges and moats
« Reply #5 on: February 09, 2010, 06:44:37 pm »

The top level walls are so archers don't plunk whoever is on it (if you have a caravan, or your military going through it).  Also, if you have people fighting on the top level, they could potentially fly/get hammered off it.

No, a raising bridge does not take a place in the sky.  The reason for using it is so it doesn't have to hang, you can place 3 more traps if it isn't hanging.

Also, for that space between the walls on Z-0, you can always set up a pump + drain system to drown whoever is in there.  Bonus points if you include carp.  Muwahaha.

Traps can not be placed on the bridge though, but if you construct floors, the traps can be placed there.

Also, you can make Z+2 an archer platform, just be careful as you do get "dead space" where your marksdwarves can not hit targets within 1-2 tiles x/y while the target is on Z-0.  They can't lean out far enough or some junk.
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I'd do that, but I don't think dwarves have words for "fair" or "logical".

JamPet

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Re: Traps, bridges and moats
« Reply #6 on: February 09, 2010, 10:53:11 pm »

I love building artillery towers facing down my entrance hallways, they are not very effective truth be told, but they are super cool.  And, on the rare occasion a ballista arrow actually makes a direct hit into the middle of a gob pack it REALLY hits.  If you wanna try it it can be a fun project, but I'd say get the main defenses working proper first.

Here some little warnings for when/if you do.

-Siege operators are civilians, put the tower about thirty tiles at minimum back from where you expect goblins to come into the field of fire so your gunners don't get spooked and run off.

-In the same vein, operators will also be spooked by retreating goblins running past the tower, even if a fresh enemy squad is just entering the field of fire.

-Crossbowgobs on the ground level might be able to see and shoot at your operators, best protect them with fortifications or, my choice for coolness purposes, a wall of glass floodgates linked to a lever (Open the artillery blast doors!...FIRE!)

-Catapult stones do not harm friendlies for whatever reason and make great training engines, since they can therefore be placed anywhere, even your dining room.  Operators need to be professional or better before they start getting much accuracy over the 30 tile range I mentioned earlier.

-Ballista arrows will explode your strongest dwarf into bits, so you should keep the field of fire clear of any friendlies if possible.

Good luck at it, tell me if you manage to nail any goblins to the walls!
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TKTom

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Re: Traps, bridges and moats
« Reply #7 on: February 10, 2010, 10:48:40 am »

Here some little warnings for when/if you do.

-Siege operators are civilians, put the tower about thirty tiles at minimum back from where you expect goblins to come into the field of fire so your gunners don't get spooked and run off.

-In the same vein, operators will also be spooked by retreating goblins running past the tower, even if a fresh enemy squad is just entering the field of fire.

-Crossbowgobs on the ground level might be able to see and shoot at your operators, best protect them with fortifications or, my choice for coolness purposes, a wall of glass floodgates linked to a lever (Open the artillery blast doors!...FIRE!)

-Catapult stones do not harm friendlies for whatever reason and make great training engines, since they can therefore be placed anywhere, even your dining room.  Operators need to be professional or better before they start getting much accuracy over the 30 tile range I mentioned earlier.

-Ballista arrows will explode your strongest dwarf into bits, so you should keep the field of fire clear of any friendlies if possible.

Good luck at it, tell me if you manage to nail any goblins to the walls!

 One important thing is that the accuracy of your siege engine is determined by the quality of the parts used to build it, NOT the skill of the dwarf operating it. Operator skill increases rate of fire only.

 Another thing is that siege engines can only fire on the same z level as the one they occupy, and only aim in a relatively small cone around their azimuth.

 http://dwarffortresswiki.net/index.php/Ballistae
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telamon

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Re: Traps, bridges and moats
« Reply #8 on: February 10, 2010, 04:30:42 pm »

Yeah, I was doing a lot of preliminary research on the wiki to determine my options. I'll try out my defense plans and see what happens, thanks for your help!
Do catapult hits strike a small area around the target? If so I might deploy 2 ballistae 1 catapult rather than 3 ballistae...
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jayseesee

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Re: Traps, bridges and moats
« Reply #9 on: February 10, 2010, 06:04:20 pm »

Yes, catapults have a little bit of "splash damage".
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I'd do that, but I don't think dwarves have words for "fair" or "logical".