So, Workedautums 1056, a random mason is installing the floodgate on my airlock-entrance to the caverns, watched over by a squad of marksdwarves and some steel-clad recruits in case of emergency.
And suddenly... POW, outta nowhere runs Urgoth Something, fast as lightning... honestly, Im running at about 5 FPS, and he's going at least 3x as fast as a dwarf. I panic and order the airlock locked down, but he's too fast; he smashes the mason 2 screens into the caverns and barrels down the central stair case into my dorms before anyones even close to the lever... the marksdwarves don't get a shot off. I order my two newbie squads to pile on (18-19 steel clads) and a massive brawl erupts, dogs, dwarves, all invisible under the neverending bursts of dust. I am worried. I still have my 6 experienced soldiers in reserve far above near the fortress entrance, but I want to keep them away from the dust if possible.
He kills a wardog and two recruits outright, terminally injures another two dwarves, but eventually he sucumbs under weight of numbers... in truth I have no idea what actually happened, all I could see was dust and I couldn't be bothered wading throught the 40+ page combat log of "Forgotten Beast is enveloped in freezing Forgotten Best extract!". For all I know he killed himself with his own dust.
Almost immediately, the rotting began.
A little word about the layout of Workedautumns... the entrance is carved into the top of a natural 7z rock spire that stands above a river gully, the sharp peak of a small mountain.
What the next wagonload of merchants would have seen was essentially a miasma volcanoe. 100+ rotting kittens and puppies tore around the fortress, and all the miasma filtered up the central stairway and eventually out into the open air, resulting in a 10z+ mushroom cloud of miasma pouring out the top of the spire and flowing down its sides. I ordered all non-pet animals butchered and the rest caged, but the fortress was in complete chaos and progress was slow.
40ish dwarves where rotting, the 10 bed hospital was full so they mostly just languised and died in the hallways or alone in their bedrooms. The hospital was just a bright purple patch of miasma on my screen... I had no idea what was happening in there, just occassional death messages. Dr Zen and Nurse Stinky both sickened and died, but Dr Best was indefatigable and worked night and day to try and save his brethren (at least I assume he did... I couldn't actually see anything, and to be brutally honest it would have been more in character of him to kick a patient out of bed and sleep his way through the crisis). It would be nearly TWO YEARS before I saw the hospital again, and when I did in every bed and covering most of the floor where dwarven corpses.
I deliberately breached the defenses in several places to try and let some of the miasma out. When I carved a hole in the roof of the hospital, a 7z cloud of miasma instanly formed above it... and I still couldn't see inside.
I had two masonshops on repeat orders for coffins, but between the tantrums and sheer number of deaths they couldn't keep up. A legendary miner struck down the legendary armoursmith, who was then himself taken down by the militia. The militia themselves (those who weren't rotting) attacked each other in their baracks, leaving arms, feet and even a nose for me to find in the cleanup years later. The wounded perished from lack of medical care. The legendary gem cutter threw herself in the river, the mayor went mad and attacked the legendary fighter captain of the guard, who funnily enough just blocked every attack until one of his men struck the mayor down with a single axe-blow from behind.
However, slowly but surely, the pets all started dieing, the tantrums died a away, and some merchants arrived (those that saw the miasma-volcanoe) bringing some much needed distraction. The population was down to about 50 adult dwarves and 10 children (from ~120). My elite squad of dwarves had only suffered two casualties, and I still had 8 marksdwarves. The most scariest fricken dwarf I have ever seen (I'll probably talk about my capt of the guard another time - The Imperial Keeper of Pages(?)) was still ecstatic (he is truly sociopathic) and I was very careful to keep him happy throughtout... I'm pretty sure he could kill every dwarf, animal and mineral in the fortress without taking a scratch.
Two years later and the cleanup was mostly complete. I'd lost most of my legendary dwarves, and of the original 7 only Chis the mason remains. The ineptness of the hastily appointed newbie broker meant I had to sell pretty much everything to the merchants just to get a decent load of sand and crossbow bolts, but he went from dabbling to master in one trading session, so the next time it should be better.
I keep finding little suprises from the crisis, however... the nose in the baracks, the dog corpses that for some reason no-one will take to the refuse, the fact that Dr Best is now a High Master diagnostician, the savage beating that occasionally get meted out, presumably for crimes commited during The Rot. But Workedautumns lives on! Now its time to return to the caverns...