Obok Meatgod is to be never spoken of again. Drop it.
Anyway, my one:
I had the grand, gold plated fortress of Astikal, Sabreheals. It was split in two - Old Sabreheals was where the peasants lived, in relative safety and warmth in the rock layer. The entrance to Old Sabreheals was through a corridor of coffins and slabs - everyone who had died in Sabreheals up to that point.
New Sabreheals was down in the third cavern layer, almost totally sealed off from the rest of the caverns except fliers. It was plated with gold and silver, or at least was going to be when I had smelted it all.
Combined New Sabreheals and Old Sabreheals had a population of 220.
Now, this fort was buried deep in a Terrifying Glacier layer. AKA, Dwarf Fortress Hardmode.
In the first two years after Astikal was established, forty-five dwarves of eighty starved to death. Food was hard to come by, and farming was impossible because there was no plants. The caverns were breached, and a further twenty dwarves died to a forgotten beast that slew them where they stood, throwing one's arm onto a butcher's shop that remained there until the fall of Astikal.
Limping along, Astikal then witnessed its first siege. A massive goblin army, most of them mounted. Their general, a demon of ash who could breath fire came with them.
The masons constructed their new drawbridge and built it faster than I'd ever seen before, and the lone, critically injured mechanic dragged his upper body up to the main levels and linked the levers.
But we didn't need it.
An infernal ash storm swept over the sieging horde. When the ash cloud cleared, all but five of the invaders were dead, their blood everywhere.
The five live ones were the ash demon, three goblin lashers and their rutherer mount.
All were covered in such massive blisters as to be almost unrecognisable. Seconds later, the three goblins died of blood loss. The rutherer just died. The demon, ashen skin still bubbling as if he were heated liquid, managed to crawl to his feet and fled the map.
From that moment on, Astikal needed no military. Every siege that showed up was wiped out by the timely arrival of infernal ash storms.
One year, humans came to Astikal. They moved too slowly. The ash clouds consumed them.
Another year, elves came to Astikal. They too moved too slowly. They were enveloped in seconds and destroyed.
But yet, the dwarves of Sabreheals still lived. A massive series of migrant waves swelled their ranks, which in time reached nearly 220. All adults had some kind of job - be it farming or mining or masonry or carpentry.
The caverns supplied the wood and plants, livestock breeding supplied meat, and so did roaming polar bears crippled by ash storms. We had a fairly high death rate among butchers, but I made sure that they wore clothing and washed as they came into the fortress - thus keeping themselves clean. Occasionally, a butcher would be hospitalised with blistering on his/her hands, but they'd generally survive after washing and cleaning and dressing.
We had a pretty decent clothing industry - Sabreheals NEEDED it, to prevent dwarves from dying from the ash storms.
But then, one year, everything changed. A hunter discovered a lost human caravan, dead to the man. He promptly took the bolts there, and put them in his quiver.
In the main stairway, which everyone preferred to use, he decided he'd take his shoes off. They were caked in ash.
He also took his socks in the entrance to the stairway.
Guess what. Also covered in ash.
Now, to get from New Sabreheals to Old Sabreheals, one had to climb up a massive staircase that wound around workshops. Everyone worked in those workshops sometimes.
Hence, that staircase was possibly the most heavily trod upon area in Sabreheals.
Nothing terrible happened until fifty dwarves suddenly sickened, passed out and were taken to hospital. They slowly developed blisters, that started on a single limb, gradually covering their entire bodies before they died of blood loss after (i presume) their blisters popped.
Naturally, more and more dwarves sickened, as well as the hospital staff. It took me some hunting to find, forbid and wall off the offending area - i had to get a miner to dig a new staircase with redundancies so that it could be sealed off. The miner completed the job, and promptly sickened too.
In all, 176 dwarves sickened and died with the ash fever, and Astikal's livelihood was irreparably damaged. No more migrants wanted to come, and the fort couldn't be run with only twenty healthy adults and thirty children.