I and 3 Archdevils will go to destroy the wall. 1 Archdevil will be the bait.
3 others will cover our rear.

Your catapult is trying to destroy the wall, -50HP,
I was destroying demons when suddenly a piece of the wall fell on me. -20HP. Yes, it seems someone is breaking it. The catapult must be destroyed, but it is covered by Archdevils. No matter. We'll smoke them out now. From the walls, dwarves are pouring holy water on the Archdevils. -70HP, they roared in pain and attacked the dwarves. Excellent. Ice block into the catapult -48HP
wall 450/500HP
catapult damage = 50hp 902/1000HP

I took the knights and went to the healer's tent... I defeated the demons (though I lost 11 knights!)...

But suddenly 7 Archdevils appeared and pushed you back -40HP and are destroying the knights-20 creatures.