Warcraft 3 Frozen Throne Walkthrough for Undead Scourge:
Chapter 3: The Dark Lady
Optional Quest: Ogre Warlord
Optional Quest: Bandit Lord
Organization doesn't matter here, just group everyone you can into groups 1 and 2, you'll probably have about two full groups. You just gained an entire army in one swoop. Get everyone back to your base, where you should be building more banshees to possess any other attackers. Abominations are great, and you can use as many as you can get. Take a group of banshees with Sylvanas and a pair of ogres to the north of your base. There is a path just outside the northern exit that leads east. Follow it. You'll see bandits, which will let you know you're on the right path. Once again, do not kill any of them! When you reach the gate guarded by a pair of bandits, bust it down and rush into their base. Follow it to the west and look for the bandit lord. He's the only soldier here with an aura. Possess him to gain all of the bandits. When they're all yours, you should have enough forces to fill four groups. Get all four groups to the south of the bandit base. This is the path that leads to red. Send everyone along this path and don't bother deviating much. When you reach the red base, enjoy watching this massive army chew them all up!