The history of the Terran Empire is, in large part, one of violence. Events in the mirror universe tend to be a dark reflection of those which occur in the Federation timeline; first contact with the Vulcans, for instance, resulted in the immediate murder of the Vulcan ship's crew and the seizure of the vessel itself. The Empire used Vulcan technology to expand; over the next century the Empire incorporated species including the Vulcans, Tellarites , Andorians, Orions.  By 2155 the Empire was experiencing some difficulties; a rebellion broke out amongst some of the subject species, most notably the Vulcans and Andorians.  The rebellion was initially very successful; at the battle of Tau Ceti alone the Empire lost a dozen ships. 
In early 2155 Commander Archer of the ISS Enterprise discovered the existence of an advanced Earth vessel which had been captured by the Tholians. The Tholians had detonated a tri-cobalt device near to a dead star in order to create an interphase rift, hoping to lure a vessel from a parallel dimension through with a distress signal. The plan succeeded, and the Tholians managed to capture the USS Defiant from the Federation's timeline. Archer tried to convince Captain Forrest to attempt to capture the ship, but was unsuccessful. Archer staged a mutiny, taking command of the ISS Enterprise and setting it on course for Tholian space. Although Forrest was able to regain control of the ship, he was unable to change the course Archer had locked in. 
On arrival, Forrest sent a team over to capture the Defiant. However, his own ship was discovered and enveloped by a Tholian Web weapon. The Enterprise was destroyed by a group of Tholian ships, leaving Archer in command of the Defiant. He managed to get the ship operational, inflicting heavy damage on the Tholians before escaping. 
Archer immediately took the ship to meet up with the ISS Avenger, which was engaged in combat with the rebels under the command of Admiral Black. The Defiant proved vastly superior to the ships of the time, and quickly turned the tide of the battle. Flushed with success, Archer murdered Black and set a course for Earth, planning to assume the title of Emperor. Uneasy with the presence of non-Terrans on the Defiant, Archer had all but Doctor Phlox moved to the ISS Avenger. 
Nervous at the prospect of having the bigoted Archer as ruler of the Empire, T'Pol and Soval encouraged Phlox to sabotage the Defiant so that the Avenger could destroy it. They then planned to turn over the information on the ship to the rebels to ensure their success. Unfortunately, Commander Tucker was able to overcome Phlox and restore the Defiant's systems. The ship effortlessly destroyed the Avenger and proceeded to Earth. With victory within his grasp, Archer was poisoned by Hoshi Sato, who took command of the Defiant and declared herself Empress. 
In the aftermath of the change of power Empress Sato crushed the rebellion, and used the Defiant's advanced technology to expand and consolidate the Empire. It would not be threatened again for well over a century, when Spock would use the power of the Tantalus field device to gain control and institute a program of reforms which weakened the Empire and allowed the Klingon/Cardassian alliance to defeat it.