How to win with a “weak” Knight?

If the hero has archers, I take them along. They're good for taking out those annoying butterflies. With the appearance of rangers, I settle them in the castle. In another scenario, I won using peasants; I wouldn't have been able to do it without them. Forsaken Lands, a king, and a Knight's castle. I somehow managed to build pikemen and swordsmen on the first level. I take a second hero, a necromancer, and use him to open the chest, advanced necromancy. On day 8, the long-awaited rangers arrive. About 20 of these guys took out a legion of peasants, and eventually, I had an army that I could use to go after the warlock. Of course, things weren't all rosy after that. I chose a knight as the main hero, there were many enemy castles, and the warlock was very strong, casting lightning spells. I had to build multi-colored flying units, and that took about 3 weeks. In the end, the battle lasted about 4 hours and took about 40 days.