The Changeling War was a conflict between the Shen and the Fatar, who used their shapeshifting abilities to infiltrate the Shen society. For unknown reasons, the Fatar replaced many key members within the Shen government and military, secretly gaining significant influence. Eventually, the Shen discovered the Fatar's plot and started a campaign to exterminate them. In a paranoid bid to purge the alien forces from their society, the Shen killed many innocent Shen in attempts to eliminate the relatively few infiltrators. Since the war, the Shen have made many attempts to wipe of the Fatar, but this has proven to be a difficult task, given their unique abilities.