Wow, holy mother of Armok.
I just had my first major fort collapse, due to flaming zombie apocalypse.
Everything was going fine in Boltthrone until near the end of the second year, when suddenly...
"The dead walk! Hide while you still can!"
I had my civilians hide in the burrow while my lone military squad (should have put more thought to it, in retrospect) stationed in front of my fort entrance. They got slaughtered pretty easily. Deciding "screw it" I enlisted every one of my civilians into the military and ordered them to bum-rush. Didn't work out, obviously.
However, all the performers still in my fort survived and are now the only ones holding out. One group of them was still dancing and singing as the undead closed in on them and killed them - I swear at that moment I heard a man with a british accent saying "Gentlemen, it has been a privilege playing with you tonight".
The other group is hidden in the barracks. The titans (modded humanoid race, not the "animal god" vanilla titans) among them are tossing fireballs at the zombies, creating a wall of flame between them and the flesh eaters.
This, on the other hand, had the side effect of the fire spreading upwards into the surface and scorching the entire countryside. Nearly the entire site now looks like Mordor; and the fire is STILL spreading.
I have no clue where the necromancers are. I saw them at the start of the siege, now they're seemingly gone; they raised a panda skeleton (elves brought one in; before you say anything, no, I didn't trade anything for the panda, unless a sword to the face counts) and a few other dead animals the zombies slaughtered, then they vanished.
A quick recording I made.
http://mkv25.net/dfma/movie-2749-flamingzombieapocalypseTechnically the fort is still standing. That last group is the only thing still holding out - and, aside from the Titans who have no need of eating, sleeping or drinking, will all die due to thirst at some point. Visitors still show up and get killed, obviously. I'll make an update when the fort does finally die.
EDIT:Won't cling on to life much longer.
Almost over.