Speak with Marshal Bluewall at the Alliance encampment near Hive'Zora.
Are you Marshal Bluewall's new recruits? Of course you are.
What are you waiting for? Good soldiers are dying in the desert. Aren't you excited to join them?
Now, get going and don't dry out on the way.
The Alliance needs every able body they can get. The Horde has been receiving a steady supply of reinforcements from the northern part of the continent, and it's been a struggle to keep up.
Let me explain the situation to you.