Your forces have been assigned to an area along the southern border of the Elven kingdom of Quel'thalas. Gul'dan, hoping to sow the seeds of chaos among the Human and Elven allies, has located a mysterious Elven artifact near the Keep of Caer Darrow. This huge, monolithic Runestone is guarded by a Human Castle on the small island located in the middle of Darrowmere Lake. You must destroy the forces that guard this relic and gain control of the Runestone for use by the Horde.
Destroy the Human Castle
Secure the Runestone
Note: this account comes from the Official Strategy Guide, which features a first-person description of each mission from the game.
Since many of the necessary structures were already in place, Urok's unit's first task was the collection of resources for the invasion. Pig farms and slaves were created at a dizzying pace; oil tankers set out southward to install a platform and collect oil. Their warships stayed close to shore with a zeppelin overhead; their stronghold and towers were upgraded as soon as their supply of resources permitted. Construction continued with a foundry, oil refinery, and a goblin alchemist to produce more fliers for the invasion. A second shipyard was erected to double their juggernaught production, and soon they had a powerful flotilla in the bay.
Six massive juggernaughts sailed out with a zeppelin overhead to spot enemy submersibles, and they began the slow process of pounding the defenses on the central island. Keeping the ship together, they made constant strikes on single targets, then sailed back out of range to regroup. Enemy ballistae were drawn out to shore for their destruction. With most of the towers removed, they then started attacking the shipyards at both villages. Many of their juggernaughts were sunk in the process, but more were constantly produced to replace them. Once the Alliance's naval power was decimated, the juggernaughts moved in close to shore on the island and removed most of the land structures to make way for a landing.
While the island was being pounded, an ogre mound went up within the Horde's base and twelve ogres were loaded on transport ships to assault the island. Resistance was minimal and soon the runestone was theirs. This sent a clear signal to the remaining humans in the other village, who beat a hasty retreat. Urok believed their might was growing daily and that their morale was higher than it had ever been, even during the destruction of Azeroth.