Princeps' Fury

Blurb

Princeps' Fury is a 2008 high fantasy novel by Jim Butcher. It is book five of the Codex Alera novel series.
Tavi of Calderon, now recognized as Princeps Gaius Octavian and heir to the crown, has achieved a fragile alliance with Alera's oldest foes, the savage Canim. But when Tavi and his legions guide the Canim safely to their lands, his worst fears are realized.
The dreaded Vord—the enemy of Aleran and Cane alike—have spent the last three years laying waste to the Canim homeland. And when the Alerans are cut off from their ships, they find themselves with no choice but to fight shoulder to shoulder if they are to survive.
For a thousand years, Alera and her furies have withstood every enemy, and survived every foe.
The thousand years are over...