And here I believed fortifications couldn't be climbed. Found myself to be horribly mistaken, as an entire goblin siege just effortlessly scaled them. 2/3 of the fort are now dead, my farms are in ruins, and most of my dogs have been killed. Poor dogs ._.
Lessons learned the hard way. I lost a kobold camp to EXACTLY that. A dwarven siege arrived astoundingly early, and leave it to them to sprint straight across the bridge and over the wall.