Embarked in an evil region where corpses quickly rise to become the undead. Burying them in shallow graves allowed me to take over the surface world, train up two fully iron armored squads. As the fortress passed 100 dwarves, they became complacent. They partied all day and night in the dining room, on top of the artifact bituminous coal table.
That party was interrupted by my expedition leader, master miner and weaponsmith. Now a corpse, that a week after his interruption of the permanent partying, I would find out had been drained of blood. I am not sure how the dwarves discovered this, as the corpse was at the bottom of the garbage chute. The culprit, I believe, as there were no witnesses, was none other than my great macedwarf, who also happened to be a great shield user, armor user, dodger, biter, liar, cheese maker, striker, fighter, wrestler, and all around badass. I came to this conclusion because he was in vampire form eating my mason in front of all 20 fully armed dwarves and 80 civilians, during the party. No one said a damn thing, because he would kill every single one of them in the blink of an eye. The mason was drained of blood. There were -no- witnesses.
My mason, now a corpse, caused several other dwarves to become corpses, and a well timed charge of goblins through my weapon traps jammed the traps long enough for the zombie horde outside to flood in. This killed my dwarves rather quickly, and I was strongly looking forward to see how much fun a legendary hermit vampire would be. I was disappointed to find that a second dwarf survived. It turned out my macedwarf had brought a friend.
Even more disappointed were my two vampires. You see, they were both miserable because all of their friends were now dead, and haunting them. This led to much attending and conducting of meetings, as well as constant fist fights between the two of them. So I did the only thing that made any sense, I appointed the legendary to be mayor and the non legendary to be broker and manager.
A year later, after the arrival and zombification of a new group of migrants, the administrator vampire went berserk. My legendary badass mayor vampire was in the midst of picking up and dropping his equipment and possibly trying to destroy an artifact table, and was thus unarmored and unarmed.
An epic battle ensued, as both vampires consistently missed and counterstriked. After a 14 page long dodge fest, the mayor punched the administrator in the heart, rupturing it, grabbed the administrator by the throat, and punched the administrator's skull into the administrator's brain.
The administrator promptly got back up and bowed to his newfound liege.
The mayor promptly went berserk.
Your fort has crumbled to its end.