Here is a list of the Codex Alera Books in Order.
Furies of Calderon (2004)
From the blurb:
For a thousand years, the people of Alera have united against the aggressive and threatening races that inhabit the world, using their unique bond with the furies—elementals of earth, air, fire, water, wood, and metal. But in the remote Calderon Valley, the boy Tavi struggles with his lack of furycrafting. At fifteen, he has no wind fury to help him fly, no fire fury to light his lamps. Yet as the Alerans’ most savage enemy—the Marat horde—return to the Valley, Tavi’s courage and resourcefulness will be a power greater than any fury, one that could turn the tides of war…