I signed up just to share this!
This is from one of my earliest forts, my second fortress, Aged Ale, met a horrible end. I was particularly proud of my fortress at the time. I had room for all 30 or so dwarves, just beds, I had no idea their were cabinets or chests at that time. Food was plentiful, as was booze, wood and stone. I decided it was time for a good strong defense.
A channel around my entrance would be fine for now. So I set to digging it, not knowing at the time that a channel would destroy the walls under it. So now my nice looking fortress was broken by a long line that breached the walls of many rooms, no matter. Just aesthetics, not incredibly important. So I continued placing. My channel was almost done, and a bridge was being laid down for merchants to come in.
Then, disaster, my poorly planned channel had breached the walls of a small pond, soon my dining room and farm plots were submerged, the rest of my fortress was saved by strategic door placing, oh well accidents happen. But now I had half a moat! Surely my defenses would be impregnable! And, as if to test my 'impregnable' fortress, the Elves attacked! A whole two squads on my 'impregnable' fortress.
It was not impregnable. They laid down frickin planks to cross my one-tile wide channel, then proceeded to murder half the fortress (I had absolutely no military), but, lucky for me I had dug deep into the earth, and had built a hallway with some forbidden doors , the dwarves behind would be safe until the Elves left. Not so, my Legendary miner was a great guy, friends with a lot of other dwarves, a lot who died. He went into a tantrum and proceeded to murder the rest of the fortress with his pick.
Then, after his orgy of destruction was done, he grew melancholy and starved himself. But, I still had one or two dwarves kickin around, both migrants, so they had no friends. My fortress would be rebuilt by these two brave young men! And then a kobold thief came and managed to kill one. One peasant was left. A single peasant. At that point I was frothing at the mouth with anger and sorrow at my lost fortress. The poor peasant was wandering the fortress, vomiting every so often on the strewn bodies of fallen comrades, and all the while I'm trying to get him to do something, he's obviously conflicted, there's literally hundreds of jobs, bury the dead, plant seeds, harvest plants, cut wood, mine, construct building. In my rush to fix the fortress I accidentally unforbidded the hallway doors, and a lone invader I could not see in the unit list because of all the dead proceeded to wrestle the last survivor to death. Aged Ale had fallen.
Heh heh, I just copied and pasted this off the story archive, I was too lazy to actually write it again!