I was playing my little fortress just a while ago when suddenly the fps drops from 100+ to around 50. Thinking that it must be the result of the filling of my new drowning trap, I didn't worry too much about it. My trap finished filling, and I was ready to try it out.
I opened my front door with a lever and waited for the first group to find my sacrificial cat or cage trap. Soon after, I got a bite: 4 or so goblins and a Kobold ambush that was unlucky enough to arrive at the same time.
And then with only a one-second pause between them (as they're discovered):


Top: My pieced together picture of the ambushes, minus the one that appeared as I wrote (don't forget to look at the right side of the picture)
Bottom: Some of the aftermath of the resulting battle
They were revealed because the Elves were attacked by the goblins, and vice versa. The Elves used a mixture of swordsmen and war giant eagles, but for some strange reason, only the eagles fought back (perhaps the ethic that prevents them from attacking neutrals?). As a result, there was a huge massacre when the Goblins saw the Elves. Unfortunately, I didn't think of taking pictures of the troop numbers until after they had all slaughtered each other.
Towards the end of all of this, a human caravan appeared right next to a squad of Goblins, who spotted a bunch of Elven giant war eagles. The eagles vanished quickly after slaughtering the caravan, some of the Goblins ended up in my drowning trap, and one Human Pikeman survived the melee.
For some strange reason, the Human is just lounging around now in perfect health. He opened up a can of whoopass on a fleeing Goblin squad, but doesn't seem to want to get out of the rain. The snatcher mentioned in the picture is lounging around too, but he was torn apart by eagles... he kinda has an excuse.
I've never gotten that many invaders
in sieges! Thoughts?
Modded raws: A couple of tags to make my Dwarves evil, Champion and DM appointed by Mayor, and a few other tags to fix some creatures (e.g. EXTRAVISION for pond grabbers). I'm using 31.16.