Sometime between 2267 and 2270, Spock becomes commander-in-chief of the Terran Empire and implements several major reforms, turning the Empire into a more peaceful and less aggressive power. Prior to the full enactment of these reforms, the Terran Empire forces occupy Bajor. Spock's reforms leave the Empire unprepared to fight against the Klingon-Cardassian Alliance. The Alliance conquers the entire Terran Empire, enslaving the Terrans and Vulcans.
Julian Bashir and Kira Nerys become the first people from the primary universe to cross over to the mirror universe in one hundred and three years. Quark is executed. The primary Doctor Bashir kills Odo.
The Rebellion takes Terok Nor. A mirror universe version of the Defiant is constructed from schematics from the primary universe. It helps the rebels to remain in control of Terok Nor. Intendant Kira Nerys kills Nog and Jennifer Sisko.
↑Berman, Rick and Braga, Brannan (Creators of Star Trek: Enterprise) editors Glass Empires (Three Tales of the Mirror Universe)--Age of the Empress by Karen Ward and Kevin Dilmore [ Story by Mike Sussman ]; Sorrows of Empire by David Mack; The Worst of Both Worlds by Greg Cox) New York:2007 Pocket Books, a division of Simon & Schuster, Inc. (Trade Paperback) Page 230 (In the Star Trek: Enterprise episode "In a Mirror, Darkly", in the introduction, the flag of the Terran Empire can be seen being planted on Earth's Moon, presumably by a mirror universe Neil Armstrong, thus showing that, in the mirror universe, the Terran Empire had been established before 1969.)