Warriors: Dawn of The War

When MountainClan receives a message from a loner group called the Flares to hand over their land in three days or they will take over, Rockypaw is uneasy about it. When MountainClan agrees to let them take it, they attack a rival, weak clan. But truth about MountainClan's High-ranked cats spills and war dawns. And the world of Rockypaw, his friends, and the Clans seems to crumble.

I do not own Warriors. Credit to Erin Hunter.