Necropolis – “Dawn from All Sides” [Campaign 2, Mission 3]

I don't understand the difficulty in progressing. The main issues for me are glitches and freezes. Until they fix the computer opponent's obsessive desire to leave guards in captured Fortresses, splitting its armies becomes incredibly easy, and the fragmented remnants are easily killed off piece by piece. The only exception is the city dwellers, but even they are not a major problem.

In the previous campaign, I didn't rebuild any cities until I had to kill the final Shades of Darkness. That's where it becomes difficult without a large army.