On my third or fourth fortress at this point having never played the game prior to the Steam release. I'd play a few hours, decide I could do some things better and then start over. I was real happy with this fortress, but just had my first siege at ~2 years in with a population of 24. I'd mostly neglected military other than a group of 3 axedwarfs.
I lost 9 dwarves in the siege, one of whom was my doctor, which is a problem given that one of the fighters survived but I assume won't live through the medical 'treatment' he's currently receiving. I think I'll keep going with this one to see how trying to recover goes.
Siege defense is pretty simple in vanilla DF. Construct a bunch of doors which, if barred, force invaders to walk a gauntlet of traps. Link those doors to a single lever. Define a burrow well behind the doors and make sure your lever is inside that burrow. Be sure the "source materials from outside the burrow" option is OFF. Start with stone-fall traps and replace those weapon traps as you craft tool components (my favorite trap component is the large serrated metal disc).
When a siege begins, assign all your citizens to the burrow, pull the lever, and put your soldiers at the end of the gauntlet. Manually cancel all current jobs from the Citizens Information Menu to make sure your dwarves aren't trying to do any tasks outside the burrow. Then you wait for the invaders to kill themselves. As long as you keep adding traps, it's unlikely that a siege will make it all the way through your gauntlet. The invaders will flee when enough of their attackers are killed.
In this layout you'll also see a bridge that I've added to provide protection to merchants if I have a caravan visiting when invaders attack. The bridge is hooked up to a separate lever. (The ballista haven't proved useful so far.)
Oops, I had to remove the weapon traps in front of the bridge, they made my depot inaccessible to caravans.
100+ goblins invade, looking for artifacts.
They're not having a great time of it.
Aftermath: Lost 1 dwarf.
If I had to redo my fortress, I would make the final leg of the gauntlet much longer and inline with a ballista, so I could pop open the doors and immediately fire a giant ballista bolt down the hallway before sending in my dwarves.
That method of defense just isn't quite satisfying enough.
Of all the many dozens I tried over the years, none could compare to The One.
Also, good lord that was 15 years ago. Game's got legs, don't she?
Current fort has seen some fun things.
One was an early migrant wave from 27 to 76 Dorfs - but 23 of the new arrivals were children.
And now I dealing with my first weresloth infestation and it is a struggle - this may be the end for this one. I'm getting much better at organising things though.
My "safe" adamantine mining is very slow going. I haven't even reached the adamantine layer yet.
I figured mining from above using channels would be safe and it's... safer, but not safe. Miners have a tendency to walk down into the channel they just mined, which often fill with magma a tick later. Because dwarves are stupid. They sometimes do this even when I have them assigned to a burrow which forbids them from going down into the channel.
When the channel releases a scary monster, the miner is the nearest target. Sometimes the miner will even attack instead of fleeing. The problem is that it's impossible to make a miner wear armor while they're mining because there's a hardcoded "uniform" for miners that replaces their outfit even if the miner is in a military squad and assigned a set of armor.
So I have to babysit and micromanage the whole process and it's tedious. But I don't really have a goal in my game other then to get more adamantine and outfit my soldiers with it.
So I've learned that if you set your soldiers uniform to "Uniform worn over clothing" then they will never wear metal boots, they will instead wear civilian footwear even when training or on duty.
Clash of the titans! The fire breathing one prevailed but set everything around it on fire.