With the Enthralled Val'kyr by your side, kill 5 Frightened Provincial Minutemen so that they can be turned into Forsaken Troopers. Then find Thassarian in western Andorhal.
You have no idea how difficult it was to stay disguised while I watched Koltira let this war slip away from us. Even now, those infernal farmers threaten to overwhelm us. All because he refused to slay a friend.
Take my val'kyr again, <name>. With her by your side, kill these farmers, convert them to Forsaken, and mobilize them. Then take a group of them into Alliance-held western Andorhal and hunt down this death knight, Thassarian.
We will win this war yet.