I had in my log one of my best failure, it was in the good old 40d
My fort was next a river that i used as a water source. I had a meeting hall and dwarves were socializing, and i think that was my mistake.
I started to notice lots of blood running in the river, checking i saw those good old DF
finest and several dwarven corpses, and more adding with time.
It was not fishing and drinking anymore, it was war, and my
fishers/drinkers warriors were losing very obviously.
After the death count slowed down and stopped, it was 15 dwarves that i had lost there in such little time.
And then i understood why making my dwarves having a meeting hall
was a mistakeIt took some time but it finally ceased after a while, but it was 20 more dwarves that met a unfortunate end, it was really insanity in there and on the surface of my fort.
40d didn't had ghosts, but still miasma was going to be a serious annoyance, and my few surviving dwarves were already on the edge enough, i didn't need a round 2 of the previous festivities.
I tried then to make coffins, very slowly as i had so few dwarves working, but the goal was to hopefully get some happy thoughts and keep my few survivors happy enough to avoid them launching a new bloody mess ... until i could get a new migrant wave to help with making some defenses, as my now very underpopulated fort wasn't going to complete the needed work as fast as it could have before the fun started.
Outside what happened was that the migrant wave was not coming, but a goblin ambush did.
Oh well, let's close the bridge ... hey wait a minute where is the lever ?
*remember the "party" * ... oh no ... oh well , i guess it was time for an end.