About a year before The Faultless Arrow began its adventures the Minthras Imperium had begun a campaign to pacify and conquer the Cleaver orc tribes. This process was fairly slow due to the large size and non-exitant infrastructure of the Cleaver lands but while the party was busy investigating the murders in Dewport, the Imperial Legion (led by Prince Gregor) forced the united Cleaver tribes into battle around Ragged Gorge.
Although the orcs had been enemies of both Rubia and Cascadia for centuries, both provided aid for them against the Imperium (Rubia sent mages, Cascadia sent cannons and muskets). In the end their aid proved to be insufficient as the Imperial Legion routed the orc army shattering what hope remained of repelling the Imperium.
The results of this battle were especially devastating for the Cleaver orcs as none of the chieftains would retreat; cowardice is not tolerated in orc society. This allowed the Imperium to wipe out the entire Cleaver orc leadership, making any attempt at regrouping impossible.