The Battle for Andorhal was a three-way battle between the Forsaken, the Alliance, and the remaining Scourge forces in Andorhal.
With the Lich King defeated, the Alliance and Horde were able to claim separate portions of Andorhal and soon after began a crusade to claim the whole city, while the Scourge tried to keep their territory. Over the course of the battle both Koltira Deathweaver and Thassarian send adventurers to deal with the remaining Scourge forces. After defeating their leaders, the two enter a truce with one another. Some time afterwards, Alliance farmers, hungry from poverty, train in the art of combat and are armed by Alliance adventurers, so that they may defend themselves against the dangers of Andorhal as they farm food from Felstone Field. Once the battle has officially resumed, the farmers planned to aid the Alliance in retaking Andorhal. Lindsay Ravensun sees the farmers training as an armed incursion and orders the plaguing of Felstone Field, using the Val'kyr to raise the dead as new Forsaken recruits. The farmers later form a militia and defies Thassarian's orders, launching their own sneak attack on Koltira's Forsaken forces. With his hand forced, Thassarian resumes the war with the Forsaken. After repelling the militia's wave of the invasion and killing some of the Alliance commanders in response to Alliance adventurers killing Forsaken commanders, Koltira sends agents of the Horde to speak with Lindsay Ravensun, whom he was told would be supporting him in the final battle.
During a battle in the city, the forces of the Horde and the Alliance fought united (while still fighting with each other) under a common goal to kill Chromie.
Upon meeting Ravensun, it is revealed that she is in reality Sylvanas Windrunner, who is aware of the truce between Koltira and Thassarian, dating back to their service as death knights of the Scourge. Using the val'kyr, she resurrects slain Alliance soldiers - many no more than peasant militia - before sending agents of the Horde to eliminate Thassarian. Many of these agents, including the Val'kyr commander, Aradne, are slain by the Alliance forces led by heroic adventurers. Despite their valiant efforts however, the Alliance are forced to retreat from Andorhal, unable to stand against the onslaught provided by Sylvanas' Scourge-like tactics. As Horde forces enter the Alliance camp, all they find is the slain body of Lurid, Thassarian's skeletal minion, and discover that Thassarian and the remaining Alliance forces have retreated from Andorhal. With Andorhal now in control of the Forsaken, Sylvanas calls Koltira to her and after berating him about his "weakness" and Arthas' failure to remove such weakness, a portal appears and a chain drags him into the Undercity, where Sylvanas promises to eliminate his compassion for Thassarian and ensure his loyalty is to the Horde and more specifically the Forsaken.