The Battle Horn

Objectives
Take the Unyielding Battle Horn from Lieutenant Commander Thalvos and bring it to Althen the Historian in Spinebreaker Post.
 * Unyielding Battle Horn

Description
Perhaps we have taken the wrong approach to the Unyielding?

The tome tells me the Expedition Armory was destroyed by orcs and death knights long ago. The Unyielding remain here as vengeful spirits trapped in an eternal battle against the fel orc clans.

They think only of revenge. We must arrange for them to defeat their most hated enemies. Enter the Expedition Armory once again and find Lieutenant Commander Thalvos. He carries a battle horn that can summon the Unyielding. Bring it to me.

Rewards
Upon completion of this quest you will gain:
 * 9800 XP (or at level 70)
 * +250 reputation with Thrallmar

Progress
We must help the Unyielding soon. If we can convince them to join us the Horde will have gained a powerful ally.

Completion
You have done well. This ancient horn will allow us to summon the Unyielding.

That is, if they are willing.