Just got sieged, all goblins from a single civ. This siege has shown up with a demon as the leader. Upon arrival, all of the goblins and beasts have attacked this demon, and its been a crazy 1 on 30 fight. The first few entries of the combat logs reference the demon as a law-giver, but soon after it is only referenced as a "coyote fiend." as soon as the goblin squad attacking the elves inside my fort is cleaned up, I'm going to send in my shock troops to wipe up whats left of the demon and his one-time comrades.
UPDATE: the fiend took out 90% of the goblin beasts and crossbowmen, but the lashers arrived and laid the hurt on it until a bolt from the last crossbowman took out its brain. The lashers are moving in on the fortress now, I'm going to pull back to the gates and let them after the elves again while my archers soften them up before I let them engage my axedwarves.
UPDATE: My militia commander and his second in command had other ideas about falling back. They charged the lashers, and killed all but 4 of them without taking a single hit. By that I mean they could have been naked but for their axes and shields and they would have still been fine. The second in command went into a martial trance, finishing the battle with 11 kills, the militia commander got 6. The marksdwarves also performed admirably.
Despite using the elves as a lure to get the goblins in range of my marksdwarves, the merchants only lost a single horse. Maybe my military is too effective.