In the mirror universe, the Klingon-Terran War was a conflict between the Klingon-Cardassian Alliance and the Terran Empire, by that point known as the Terran Republic, which ended in the conquering of the Empire by the Alliance and the liberation of the races formerly enslaved by the Empire. The war took place in the year 2295, ending with the Battle of Earth. Emperor Spock and Empress Marlena Moreau are killed by Alliance troops.