I established a fortress on a mountain tile, unwittingly knowing that a deep, open-air chasm lay nearby, populated with antmen, batmen, and of course the dreaded naked mole rat. Normally, it wouldn't be a problem, but the map's closest source of wood lay right next to the chasm area, so my herbalists/woodcutter constantly spammed job interruption messages thanks to the batmen that would fly up to the surface to observe my dwarves laboring. In particular, there was one batman that would go so far as to come out of shelter of the cave and into the daylight to terrorize my hardworking dwarves. Finding this tedious, I recruited my woodcutter and sent him to attack the batman which was currently standing near the edge of the chasm. In his fervor, the woodcutter smashed into the batman, knocking him out and sending him flying down into the chasm, falling 13 z-levels into the dark depths of the underworld. Unfortunately, my woodcutter's momentum was not easily stopped, and he ended up falling 8 z-levels onto a ledge next to the chasm, where he was knocked out and slowly wrestled to death by 2 antmen and 3 batmen.
I sent my miners to avenge his death a season or two later, and they eradicated the antmen from the chasm, as well as taking one or two batmen with them as well, then sealed up the passageway with a locked door. When the first round of migrants came, I still hadn't retrieved the axe he came with, so I designated a peasant to be a woodcutter and opened up the door to let him get it. I then went off to manage some workshop plans and other things, and, before I knew it, I had 4 new migrants killed by a giant cave swallow. Apparently, in unlocking the door, the peasant had told his friends the news of clothes and other free items to be had in the depths of the mountain and they came swarming in to meet their doom. I cleaned up the mess, got the axe, killed the cave swallow, and sealed up the room again to avoid another such catastrophe, and had forgotten about it until I recieved the message:
