The siege finally came, while the human caravan was halfway across the field to my gates. A little under a hundred goblins, about a dozen trolls, none of them mounted, so it wasn't my largest siege. Still, it was a mess. I took two units out into the field, too late to save any merchants, and every one of my soldiers survived. I didn't even lose a recruit.
Well, not counting the miner I recruited because it looked like he was tough enough to make up for his stupidity. He was startled by a kobold thief that had snuck through, and retreated along the deathtrail right into the arms of lingering axegoblins and hammergoblins. He promptly whacked one of each with his exceptional steel pick, before getting knocked off the cliff into a ditch filled with stunned and broken goblins and trolls.
But it was less than half full of cooling magma, and he survived. And he took out another troll and a spearmaster! He crawled into the drainage which was still blocked with scattered with lava patches, while the invaders were taking blasts of boiling blood of their comrades. I'd finished off the aboveground and stationed a fresh unit to the hatch until a path cleared in the lava down below, and put archers on the bridge over it.
The miner seemed to be doing well in spite of everyone's unwillingness to fight, but I figured if enough came to and got up the courage, they'd swamp him before I could get a rescue down there. So I recruited him into a militia and stationed him next to a dazed goblin.
He immediately dropped the pick he owed so much of his survival to, ran over to punch the goblin a few times, and got hacked across the throat with an axe. What a pity.
Well, the lava is still cooling, and the squad is still twiddling while the few archers that could be bothered to show up are cherrytapping the crippled gobbos with bone bolts. I could just flood the ditch, but I guess a decent burial is the least the dumb bastard is owed.
EDIT: Ah, but the law giver human who'd made it safely through and finished a meeting with the count...many times I've seen him take the perfectly safe subterranean exit, which was clear and open. Instead he just had to stroll through the cluster of routing axemen. So that's yet another human body on my doorstep, head detatched. I don't think the humans are sending a caravan next year.