Heh, well there was a lot of unhappiness. A forgotten beast broke up through the forge or a furnace, I think. At least, there was no other way for it to get inside from below, and quite a bit later I found another FB in the forge room with all of the furnaces and forges gone. Since I had been very pre-occupied, I can't say when the damage was done. At any rate, this forgotten beast appeared in the stairwell from the forges. I saw the liasion arrive at the same time and I evacuated everyone from the fortress. I wanted the Dwarven caravan to deal with the FB. Almost everyone got out. However, unbeknownst to me, the caravan had been ambushed right at the edge of the map and never actually officially entered. I found the remains of one trader and that was all, when the dust was settled.
The forgotten beast was hanging inside the entryway and would not come out into the open, past the bridges and all of the traps. I drafted my seven miners, the founders, into a pick-wielding squad and sent them at the FB. The idiots wanted to run down and drop their picks so they could pick them up again, before they did anything else! They all ran into the FB in great disorder, but finally managed to kill it. Presumably they used their fists, or maybe the hafts of the picks. Only two founders survived. I let everyone back into the fortress, but after only about half had entered, one of the founders threw a tantrum and destroyed both of the bridges. Since I was supervising burials at the time I did not realize this until I got messages that Dwarves were dying of hunger. I had someone grab a pick and dig a by-pass of the bridge area. Everyone outdoors was saved, who hadn't already died of hunger, but that was already too many deaths. I was down to about 60 Dwarves, from close to 200, by the time I got everyone calmed down. I had the bridges repaired and the by-pass sealed. Life was shaky but improving. I even had one surviving offspring of the founders, all of whom had died by then. It was during the tantrum spiral above that the kid claimed the butcher shop.
Then a Vile Band of Darkness arrived. No problem, I thought. Their Axe Lord ran un-impeded across 21 lines of weapon traps made with three iron trap components each. It was like the traps weren't even there. He slaughtered almost everyone. I released my three vampires in desperation, then realized I should keep one safe to preserve the fortress. I managed with much difficulty to get him back into his cell and had him wall up the door from the inside. In the end, I had him, one female Dwarf, and three offspring which were not hers. I'm not sure why the goblin axe lord left without killing the last four normal Dwarves.
I'm rebuilding from there at this moment.

The new migrants are all relatives of the surviving female, and furthermore they provide links between several families who had been classed as separate clans prior to the disaster. In the end most of them will probably turn out to be her relatives, including the three kids who came through it with her. I did try last night to enter them into ancestry.com, but I got a headache part way through so I quit for the night. I'd like to see what Ancestry's link-finding routine does with those names.
