The beginning of the War.

To capture a castle, you need to think carefully, really carefully. Here's a small hint: you can find help by turning right before the garrison. Think about it, look at what bases I gave the hero. You can also level up the hero quite a bit before storming the castle.

The hero is a high level, level 21. But not a single unit makes it to the demons. They are sitting in the city, and the catapult hits everywhere but the gate, as usual. Paladins stand in the moat opposite the breach in the wall and... succubi one-shot them.

 

Added 6 minutes later
On the twentieth attempt, the city was captured, thanks to the hellhounds running out of the city, thus opening the gates. But the losses are simply enormous. All the archers, half of the inquisitors, and the knights. Let's see what happens next...