Fortress saved by the crazy elf
My first fortress (that I didn't immediately let succumb to wolves or oceanic flood) was beautiful, lovely geometric bedrooms, and a z-level just for making microcline thrones (so much microcline!). I didn't really understand the trade system (just stole everything off those sucker humans), didn't really understand the military (only marksdwarves, no bolt production), but I'll be damned if everyone didn't have their own personal luxurious throne.
So the humans eventually retaliated with a siege, and all I know how to do is sit there with 10 untrained dwarves waving unloaded crossbows at 20 men with cheetahs across my pathetic bridge defense.
I hunker down, and hope to wait them out, and watch my reserves slowly dwindle. Bunches of naked children go crazy, morale drops, ghosts start to appear, and I get ready to just abandon. Suddenly, the humans leave, and everyone breathes a sigh of relief. Bridge lowers, and everyone starts excavating dead lizards and whatnot from my stocks to outside. And then goblin siege. 30 fucking goblins run up with trolls, killing 20 dwarves before I can mount a hasty retreat. I finally figure out what bolts are, but I'm out of food, booze, and happy dwarves. Then, a lone elven merchant with his mule cart walks up the cliffs near my fortress, I pause, and see he has 200 steel bolts on the cart. And 30 goblins + trolls between him and my entrance. Fuck. Immediately, probably upon seeing my idiocy, "Flgrthon, merchant has gone berserk!"
After 2 seconds of jumping around slapping his mule, the mule kicks him to death, and runs off to be slaughtered by a troll. Dig a quick hole through the cliffs, my militia grabs all the bolts they can carry, then runs off the goblins without so much as a flesh wound.