The Mirror Universe is was home to the Terran Empire from the 2100 onward but that empire became the republic under Spock's reforms.
This didn't last as the KlingonCardassian Alliance rose in opposition to the power and dethroned it, replacing it as a militaristic organization based on conquest.
By the time of Star Trek Online, the Terran Empire has returned to full power and replaced the Alliance as the dominant power, despite the best efforts of individuals to steer the Terrans towards a more peaceful outcome. But how did this happen?

Star Trek Online is full of stories and callbacks to the TV series of days gone and to come. Set in the Star Trek universe's 25th century it places you in the center of these events in an ever expanding series of tales.
Join me as I fulfill the role of a Starfleet captain and Temporal Agent, Mark Hale from the 23rd century now facing fresh challenges along the Cardassian Border aboard the USS Armiger and USS Dunkirk.

If you liked this there's always these to try out:

Star Trek Online Chapters:
Klingon War: https://goo.gl/GXLZnN
Romulan Mystery: https://goo.gl/DpGnmb
Cardassian Struggle: https://goo.gl/UtyfT8

Games
Alien Isolation Playthrough:    • ALIEN: Isolation Playthrough: Amanda ...  
SOMA Playthrough:    • SOMA Part 01: Say Cheese?  

"Failing Defense" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0 License
http://creativecommons.org/licenses/b...

Music from bensound.com, purpleplanet.com and freesfx.co.uk
Star Trek Online developed by Cryptic Studios and Perfect World.
Star Trek Enterprise/Voyager/Deep Space Nine/Discovery and The Next Generation are all owned by Paramount Pictures/CBS and distributed by CBS.
This Video is for educational purposes with commentary.