This isn't as depressing as a lot of the stories you all are telling, but it's still a shitty way to die so I'll share it anyway.
I started a new fortress recently so that I could try a few different things with magma. Anyway, I painstakingly went through the embark menu (my first time customizing
), picking and choosing what skills I thought I'd need, making sure everyone would be useful starting out as well as being able to keep up once I was established.
Anyway, I embarked, chose a promising-looking hill, and immediately began carving a home out of it, as I dislike staying out in the open any longer than absolutely necessary - and by "absolutely necessary" I mean "the time it takes my miner to walk over and start mining".
Things went well for a year or two. Building off layout plans from my previous fort, I quickly got individual rooms up and running as well as a few industries, my accomplished masons and carpenters pumping out furniture while my miner busily chipped away, carving out some lower-level storerooms. The area I was mining was comprised mostly of marble, which, combined with the quality of the furniture and rooms, attracted a full wave of 20 immigrants in the first wave.
My fort was doing well, and I had big plans for it. I'd gotten a metal industry up and running, smelting whatever ore I could find and get from caravans. My infrastructure was holding its own, I had a farm up and producing more than enough food, and my miners (I got another one in a migration) were busy digging a channel halfway across the map and down a couple z-levels to get fresh drinking water into my fort.
Only... I'd gotten so enthusiastic about the inside of my fort, I forgot entirely about the outside. I had no military, and no defenses to speak of save for two marble doors between the heart of my fortress and the outside world. (I'd been planning a magmafall + magma moat + iron drawbridge as soon as I had the metal, but it wasn't anywhere near constructed yet.) So when a kitten who happened to be wandering outside spotted the goblin ambushers, I thought I was absolutely hosed. I ordered all my dwarves inside and activated the only defense I had - I flagged the doors leading out as forbidden and waited for the ambushers to go away.
I'm not sure if they eventually did or not. What I am sure of is that 36 hardy dwarves burn through alcohol fast, and without me realizing they drank it all down in a month. Time passed, and I got sidetracked doing something else. When I got back, I forgot that I'd forbidden the doors. I went about playing, designating expansions and improvements.
By the time I realized what happened and opened the doors, 27 of my 36 dwarves, including the entire founding 7, were dead from thirst. The rest made a mad dash for the partially-constructed channel. Three more died en-route, leaving me with only six dwarves, most of which were useless (soap maker, lye maker, dyer, etc.). Rather than trying to salvage the fortress, I abandoned it, knowing that the remaining dwarves would probably have just tantrumed to death.
I like to pretend that they went back to the Mountainhome, never to leave again. I just find it sad that so many dwarves died and a promising fortress had to be abandoned because:
A) One stupid mistake on my part
B) Not one single dwarf, despite slowly wasting away from thirst, would dare cross the threshold of a forbidden door, even to save their own lives.