40d:Defense design

This page is one of several inter-related articles on the broader topic of defending your fortress and your dwarves. This page will focus on the physical layout and architecture of a fortress - specific suggestions, examples, diagrams and discussions of combining walls, fortifications, tunnels, channels, bridges, and terrain into a defensible whole.

See the Defense Guide for a general overview of threats and considerations for fortress defense.

For suggestions on training, organizing and deploying soldiers and militia, see Military Guide.

Many defenses rely on complex traps as a central part, that are, essentially, the defense themselves. For complex traps that are not a minor/optional part of a larger defensive plan, (but might be adapted or plugged into one) see Trap Design.

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Editors & Contributors - Please include diagrams or clear and well-sized http://www.mediawiki.org/wiki/Help:Images images if appropriate. For diagrams, use standard Dwarf Fortress symbols for your diagrams - an x is an up/down stairwell, a ╬ is a fortification, a ▲ is an up-ramp/slope, etc. etc. For screenshots, use the standard tileset, not a custom one that few may recognize.

If your design involves a complex trap, simply label it as such on the diagram, for example "magma trap", "drowning chamber", "hall of spikes" or "ground zero". If you wish to detail that trap, please add that (perhaps with a specific link) to the Trap Design page.

If your suggestion is lengthy and complex, consider placing it on your User: page with simpler explanation and a link here.

Lastly, if you can keep similar or alternate suggestions grouped within like subsections/topics/categories, that would be a good thing. Future wiki users and DF players thank you.

Control Room

Have one (large?) room (or several stacked on top of each other) for all defense-related levers, and central to idle dwarves - near your meeting areas and nobles quarters, with one or more halls or stairs leading to it for quick access. Connect a lever to all those doors and hatches as the first lever to be pulled in an emergency, and the respondent will lock themselves in for you, guaranteeing that they will then have nothing else to do but stay there and pull levers.

It may also be an idea to have a second lever to at least one door, for emergency access. And possibly to add a stockpile of booze and food or a well for longer sieges.

AI abuse

Taking advantage of the game's Artificial Intelligence and pathfinding is a whole article in itself. Try leaving a door un-forbidden during an attack. When the bad guys approach the door, forbid it, and the enemy will wander off. Unlock it again, and they turn around and head back towards the door again. You can get enemies to march back and forth over a set of traps this way, or lure them deep into a complex trap. This could be automated via pressure plates. This might count as an exploit, or not - that's up to you, and what you consider fun and challenging.

Airlock defenses/buffer zone

Build two walls, each with a drawbridge. Build the trade depot in the buffer zone between them. Keep the outer bridge open, and the inner one closed. When the merchants appear, put crossbows on the walls to guard their approach. Once all the merchants are safely inside, close the outer bridge. Once there's no enemies left in the buffer zone, open the inner bridge so your civilians can start loading up the depot.

The airlock pattern can be useful even without putting the depot there. Let a few siegers in at a time, and crush them. Reset the traps, Rest up the soldiers, and repeat.

Roach motel

Build a long, narrow, and twisty passage, accessible from the outside, but unconnected to your fortress. Build as many simple traps as you like. Place a bait animal inside. Enemy attackers walk right in, and get torn apart by the traps. If any manage to make it to the end, and kill the useless animal, they're surrounded by traps, and no closer to your fortress.

If the roach motel is deep enough underground, you can build a tunnel above it, channel down, and mark the channel a pit/pond. That way, you can "reload" a new bait animal.

Pathing slowdowns

If you're playing on a low-powered machine and you close up all entrances to your fortress during a siege, your game may grind to a halt and/or crash as the siegers continuously fail at pathfinding into your fortress. Bait animals may alleviate this.

Meeting hall as defense

TACTIC You can use a meeting hall zone to attract animals to a given area. This makes a pretty poor defense in general, but in the very early game, it's a way to defend your wagon and stockpiles from thieving animals. Remove the zone later, or it attracts idle dwarves and children.

Guard towers (aka pillboxes)

Build a tower specifically to post archers on, possibly away from your main defenses. This lets you open fire before the enemy approaches your gates. A pillbox can be attached to your walls, or separate, so that the only access is from tunnels below. Thse tunnels can stretch across the map, and only need be 1-tile big if no regular traffic is expected. Construct fortifications on the second or third floor, so your dwarves can fire out. For extra usefulness, build a barracks, archery target, food stockpile, well and dining room in or near the tower. Add a door or hatch to lock them in.

Siege engine turrets

If it's big enough, build a siege engine inside a pillbox. The device needs to on the same lever as the target it will fire at, but this could be across a large gap to a nearby plateau. Only a single tile of fortifications is needed to fire through the wall. You will want to guarantee that enemies do not approach the position and scare the civilian operators - dig a moat, remove some slopes or build some secondary fortifications to keep enemies at a distance. Position the tower to fire where invaders tend to congregate. Since siege operators are civilians, the "dwarves stay underground" order must be off unless this is built as an open room under a ceiling.

Fortunately, siege engines can fire through fortifications, just like normal projectiles. Unfortunately, fortifications will protect enemies from your archery fire (but not siege engine fire.)

3 Bridges

An example of some advanced defensive construction tactics to deal with vile forces of "any" size. (See picture).

• Bridge 1 seals off the entire base
• Bridge 2 forces everyone to take the long, winding, heavily trapped path of death.
• Bridge 3 seals the inside of the fortress

Clever triggering of the bridges allows you to break the hostile forces into smaller chunks to be trapped in the courtyard while being caught in traps and a crossfire of arrows from the fortifications around.