How long do sieges last?

Solution 1:

The wiki doesn't know, so it's safe to say that that is one of Toady's secrets.

After being sufficiently "successful" at defending against the siege (killing sufficient attackers, waiting them out, or some combination thereof), the attackers will retreat. All of the remaining squads and groups will head for the map edges and leave, typically favoring the edge they entered from. Once the last of the siegers leave, the "SIEGE" tag will go away.

Source: http://df.magmawiki.com/index.php/Siege

However, the 40d page states that if you do nothing, it will take a very long time for the siege to end.

The siege will end after some (LONG) time have passed,

Source: http://df.magmawiki.com/index.php/40d:Siege

Solution 2:

Waiting out a siege is a poor way to deal with invaders. I find that the best way to deal with enemies is to use the "hallway of doom" technique. This is where you have a long, twisty path that invaders full of death dealing devices that leads to your fort. They mention it on the wiki under Defense Guide.

Here are some of my favorites.

• Lines of Cage traps. You can later setup a "death pit" where invaders become "target practice" for your marksdwarfs. Easy to setup and useful in the early game.
• Carnival shooter. Where you have a large room with a switchback path that a number of marksdwarfs can watch over and fire at their leisure as the invader passes.
• Drowning locks. Again use the switchback, but setup some floodgates to both seal the room and open passage to a water source. Invaders drown, but you have to figure a way to drain the room. Can also be used with magma.

I have found that a siege could last for years and is generally better to take care of quickly. Always give invaders a path to your dwarfs, but make it so long and dangerous that only giant armies can make it through. Simply add a floodgates at the final choke point and with a flip of a switch, you can seal in the invader.

I have not tried capturing a siege in a way that keeps my dwarfs safe, but doesn't end the siege... I wonder if it will prevent another siege from occurring?

Have fun

Solution 3:

Even if you do nothing, goblins will eventually get bored and go home on their own. It may take more than a year, and most likely your dorfs will have emo'd themselves to death in the meantime because they can't go outside. Plus, while they're hanging around, no merchants will show up. If you're reliant on merchants for something important like wood, this may present a problem.

However, it is usually much more effective to try and kill some of them. A siege squad that has lost its captain or more than half of its members will usually retreat. However, a siege squad whose captain has been caught in a cage trap will just stand around him, effectively forever. If you can arrange for the marksdwarves to be able to shoot at them while they're standing around, this should work quite well.