well i had some starvation going on... had only a few dwarfs in the food produktion chain but on ongoing migrants i had some lack to feed them. about 160 dwarfs with a few cooks, fishers, farmers and only one kitchen isnt enough :>
also i totaly ignored the nobles and their demands/mandates... i lost the two predecessors of my duke in berserks (i.e.:
http://img225.imageshack.us/img225/716/countesswg6.png) and had no prison.
as far i can put out of legends and what i have seen it has to do something with stray bolts, as most of my (goblin surviving) military are the markdwarfs.
my duke maybe was tantruming (again) and killed the dogs, the guards instantly killed the duke, now the consort got mad and attacked them, the guards defend against the consort.
now the royal guard intervened and shot at the guards. so most guards where swordsman, and royal guards where marks and hammers. the one of royal guard missed the guad with a bolt and hit a military marksman. so a little fight started in the dining hall (second pic) after some peasants going to eat here, one was hit by a stray bolt of the military. the military now was declared an enemy of my fortress (in legends) and other military intervenend... more bolts.. as someone gets an enemy, he starts to kill off random dwarfs. now the guards spread in... more bolts fly... most of military standing down and the champion wrestlers and some other militarys were going to eat in the dining hall, as the they spotted the enemys (all that killed some civil dwarfs with stray bolts) they startet to fight... now even more bolts and it ended in a huge masacre. about 60 dead dwarfs from 150
i abdonned the fortress now, as for my game i always start with one female dwarf as "Rhenaya" as bookkeeper/animal trainer and reclaim her as "me" so if she dies, the fortress is lost for me.. she is the sweet clerk sitting in the middle of dining room.. thats why you see pack of war dogs in the upper level going towards the downramps xD