Princeps' Fury - Jim Butcher

After bitter fighting, Tavi of Calderon has eventually forged an alliance with Alera's oldest foes, the savage Canim, and he must escort them on their long sea-voyage home. This will strain their fragile accord - but the worst is yet to come.The inhuman Vord have spent the last three years laying waste to the Canim homeland, making it a desolate place indeed. Then the Alerans become stranded there, cut off from their ships. The Canim alliance will be tested as they enter the killing fields together, depending on each other's strengths if they both are to survive.For a thousand years, Alera and her furies have withstood every enemy, and survived every foe. The thousand years are over.