After the first goblin siege that we faced through fortifications with a good supply of +bone bolts+, we placed some cage traps around the entrance.
Next siege arrived half a year later, ending up with 12 filled cages of raw goblinite. As we found it a little bit boring to process goblinite purification manually (by dumping items from cages), we decided to setup a training room for military.
A special !!Scientific!! room was built, separated in half with a fortified wall.
Marksdwarves were stationed on one side of the wall, raw caged goblinite was placed inside the bridge-enclosed room behind the fortifications. Lever was pulled, to release the flow of goblinite.
Seconds after, Squad leader armed with legendary artifact crossbow got shot in his head, and departed to the MountainHomes of Armok's Heaven.
A horde of haulers tryed to enter the room immediately being scared off by armored goblins behind the fortifications. Military fled, room was sealed, now we are planning to make this a drowning chamber, or try to do a cave-in into that small room.
Another pack of goblins were spotted outside, paired with some trolls, so...
Seems like now we are running the siege on a small goblin fortress inside a dwarf fortress sieged by goblins. We would need a caravan from MountainHomes to arrive and close this loop. They will try to fight goblins, which are trying to siege dwarves, who are trying to siege goblins within their own fortress...