Walkthrough: Heroes of Might and Magic IV: Winds of War

This is the worst campaign I've ever seen. The map design is terrible, and it's just a constant "kill them all" scenario. I never understood the point of some of the maps – when, after a couple of in-game weeks, an enemy shows up with an army three times larger than the player's.

Either I'm a noob, or I'm missing something. I haven't completed a single campaign, but I don't regret it at all.