Speak with Penumbrius at the Argent Vanguard in Icecrown.
Across the Valley of Echoes, west of here, and through the Breach, is the first Scourge encampment in Icecrown known as Scourgeholme. We fought a good fight at Scourgeholme and killed many Scourge, but in the end we were forced to retreat. Many soldiers were left behind - their fate unknown.
If there are survivors, we must attempt a rescue. Directly down this southeastern path is Penumbrius, ally of the bronze dragonflight and caretaker of the proto-brood. Seek him out and ask for his assistance.