So, the house is all quiet, everyone is asleep but I, so I'm playing dwarf fortress and eating a chocolate orange.
I was a bit disappointed that the goblins hadn't sieged me that winter, especially with all the work I had put into a new and improved drowning chamber. But lo, in the middle of summer, a force of darkness shows up - goblins, with a substantial amount of trolls *and* the foulest of them all, an elven recruit!
I launch into action - the alarm is sounded, dwarves run back inside (little timmy hoisting a barrel takes forever, but he makes it) and the drawbridge slams shut. At about the same time, I open a secondary drawbridge - a long winding tunnel is now the only path inside the fort. The goblins fall for it, and start snaking inside. I move a squad of military dwarves near the alternative entrance, just in case.
After a while, the goblins are all inside the tunnel (and, unknown to them, drowning chamber) - just in time too, the trolls are moving fast and getting close to entering the fort proper. I give the order to close a third drawbridge to prevent escape, but nothing happens - aha, that lever is outside the "safe" area designated by the military alert. I cancel the alert. A dwarf starts moving - towards the lever I imagine. Then 2, then 10 - what's going on??!?
My dwarves are now trying to reach the surface through the snaking tunnel/drowning chamber - ie through a wall of goblins and trolls!
It did not go well. I finally managed to activate the drowning chamber, but not before losing a number of dwarves. I wasn't able to extract all of them from the tunnel. I lost 14 dwarves that day - and now I have a *ton* of crap to deal with - the belongings of all those dwarves, plus about 75 goblins/trolls...
Alarmingly, I know from previous invasions that the troll fur loincloths will prove very popular with the dwarves...