Mr Frog's estimate is very accurate. We have few soldiers, and those who survived are the lazy ones who slept through the sieges, or were knocked out by the screams in the beginning. Out of 80+ fighters, we have about 20 left, half unconscious and the other half injured.
As for the spawn numbers, that screenshot near the end was taken after the army had fallen. That would be 61 spawn. We killed... 4 of them? No matter what we do, we aren't getting an army up that can deal with them in order to reach the next banshees. Even by drafting every single dude in this fortress. The good news is that the children, despite being absurdly worthless, provide targets for the scream, meaning we may have a way of buying more time for the SPIREGATE by burrowing all the useless little kids on the top level of the fortress while the adults work deep below.
I have another plan, tho, that I shall put in motion while I wait for water to cool the magma sea around the spire. Our miners will be rather useless during this period of time, and I'd rather have a contingency plan. It's not as reliable as unleashing demons on the surface (Which is a depressing and scary sentence in itself) but it's better than nothing. I'll sleep on this, and see what I can do with a refreshed mind.
Ps: All my plans revolve around the assumption that the clowns wont be best pals with the banshees. Tell me it's true. Please. Will the banshees attack demons ans vice versa? Will they... scream... at them?
Suddenly Im not even sure we need to ''free'' the demons. Merely dragging enough of them into a trench thats right underneat the surface and goes around the map could act as a ''scream target buffer''. With demons, children, and deeply aggressive animal husbandry politics, it maaay be possible to keep the banshees occupied with random targets until they get bored.
PPs: I am, quite evidently, way past the point where ethics factor into any of our decisions.