In the mirror universe in 2155, the Terran officer Jonathan Archer seized the USS Defiant, a starship from another universe's future, hoping to use it to make himself emperor.
In the Terran Empire, Commander Archer learned that the Tholians had found a starship from the future of another universe, the USS Defiant, which had fallen through interspace from the year 2268. He took the ISS Enterprise from Captain Maxwell Forrest in a mutiny and led it into Tholian space to capture the ship.
The ISS Enterprise was destroyed by the Tholians, but Archer and a group of survivors got aboard the Defiant and brought its weapons online, far beyond anything in the Terran fleet. With it he crushed a rebel force and set course for Earth, planning to take the throne.
Archer's ambition was cut short by the people around him. Hoshi Sato, who had become his lover and ally, poisoned him, took command of the Defiant and declared herself Empress of the Terran Empire. The episode showed how the brutal Terran Empire rewarded treachery at every level.