Simple story, your commander has sent you and a great deal of Troops to Khaz Modan. In an earlier battle, you defeted the Orcish Horde, and out of fright, the Horde's Demons and Skeletons that were still living joined your army. The Horde's settlement has a large number of troops, also, so you will have to be quick in commanding your soldiers to war.
PS: I have discovered a few flaws in my Previous PUD, "Hedge Maze." If you won that scenario without chopping down trees, EMail me. I think I accidently make a path (that brings you to the end) too narrow. Let me know.
Preview of PolarPUD #3: The Gauntlet
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The Alliance is discovering that Vin Favor is bigger than they thought. In fact, there seems to be very many climates, including snowy plains and barren deserts. In this scenario, your troops are in an odd region of Vin Favor where the desert and the mountains meet. The narrow valley between the mountain has a large number of orcs guarding their base, which is just beyond the valley that separates you from it. Your mission is to pillage and plunder their village, and save the captive Uther Lightbringer that they have kidnapped.