Worshipper – “Ship” [Campaign 2, Mission 4]

I played it like this: I captured the lower Elven city, then immediately went to the Demon city (otherwise, the army keeps losing units). Then I killed some Elf and bought him in the tavern (he carried my army so it wouldn't get lost). Later, I captured two more Elven cities and started developing the Demon city. I brought 100 archers to the dragon and killed the main city with almost no losses.