Star Trek Expanded Universe
Mirror War
The Federation fleet advances to engage the Terran Empire
Date: 2380 - 2381
Location: Alpha,Beta Quadrants, and Mirror universe
Result: Federation victory
Federation Terran Empire
Various including Admiral Nicholena Tracy, Captain Jermaine Allensworth, Captain Jean-Luc Picard, Captain William T. Riker Various including Emperor, Empress, Admiral Kathryn Janeway (mirror), Captain Jermaine Allensworth (mirror), Captain Jean-Luc Picard (mirror)

The Mirror War was a conflict fought between the United Federation of Planets and the Terran Empire from 2380 to 2381. The Empire fought to extend its reign into another universe and the Federation fought to remain free of tyranny. (Star Trek: Odyssey)


The Terran Empire became aware of another universe in 2267 when Captain James T. Kirk and his away team were accidentally transported over to the other side. After that, the Empire became interested in how to duplicate that incident on a larger scale and did not succeed until 2380 when the Empire invaded the Talos star system. (Star Trek: Odyssey: "Advent")

The Mirror War begins[]

The opening battle occurred in the Talos star group initially between the USS Alexandria and its mirror counterpart. More ships arrived for both sides initiating an all-out war. The battle ended in a Federation victory by pushing the Imperial forces back into the Mirror Universe. (Star Trek: Odyssey: "Advent")

The Terran Empire went on the offensive, entering the primary universe and attacking Federation starships at random. They would even come over the primary universe and set up a base camp on random planets. Most of which resulted in victories for the Empire. (Star Trek: Odyssey: "On The Line")

The first major battle between the two sides occurred at Betazed when the Federation's ninth fleet was caught off guard by the Empire that originally resulted in a victory for the Terran Empire. Out of a hundred twelve ships, only thirteen ships made it out of the battle. Meanwhile, the sixth and seventh fleets were leaving Starbase 211 heading to Betazed. Seven of the thirteen ships were severely damaged and they returned to Starbase 211 while the other six merged with the two fleets and headed back to Betazed. After a fierce battle, Betazed was retaken by Federation forces. However, during the battle, the Terran Empire attacked the Utopia Planitia Fleet Yard. (Star Trek: Odyssey: "Where Angels Fear to Tread")

The Federation made its first incursion into the Mirror Universe when the USS Alexandria sent an away team to the Beta Antares Ship Yards in retaliation against the aggressive move at Utopia Planitia. The away team of four was to get in, destroy the ship yards and get out. The mission did not go as planned as once the away team reached the planet's surface utilizing orbital skydiving, Imperial forces were converging on the Alexandria, forcing the ship to leave their team behind as they retreated to their own universe. However, while the Alexandria was waiting for the signal from the away team, they picked up a transmission spoken in Temarian but using Imperial history instead of Temarian history. They also picked up a radiation surge that turned out to be a cloaked Imperial Prometheus-class ship. After destroying the Imperial ship, Lieutenant Commander Hoshi Sato traced the transmission all the way back to Admiral McKeen, who had been replaced by her Imperial counterpart. It wasn't long afterwards that the away team completed their mission and returned to their ship. (Star Trek: Odyssey: "Spectre's Rose")

The Empire had landed large numbers of troops on the Ba'ku planet. Crews of different starships were sent to the planet to rid the planet of the Imperial forces. (Star Trek: Odyssey: "Requiem")

The Empire continued to put their own in the places of their primary universe counterparts. Counselor Christine Nycz was replaced by her mirror counterpart and was held captive on Ceti Alpha V until her rescue by Captain Jermaine Allensworth. (Star Trek: Odyssey: "Thirty-one")

The Empire even made a brief attack on Earth nearly destroying the southeastern seaboard of the North American continent. (Star Trek: Odyssey: "Sands of September")

The Federation made an offensive strike against the Empire in the mirror Chin'toka system. The battle was in the Federation's favor until reinforcements for the Empire arrived and severely crippled the Federation fleet destroying multiple starships, including the USS Alexandria. The Terran Empire also took Cestus III shortly after the battle. (Star Trek: Odyssey: "Distant Stars")

The Imperial hold of Cestus III lasted a few months while the Federation made repeated attempts to retake the planet but it was to no avail. It wasn't until Commander Alexander Merriell, who had infiltrated the Imperial defenses and was undercover during the occupation gathering information. Once he gathered all of the appropriate information, he sent it to the sole ship hidden in orbit, USS Titan, who was able to take out the defense grid, and with the help of the other Federation starships entering orbit, the Federation was able to retake the planet. (Star Trek: Odyssey: "Catalyst of Sorrows")

The Federation also sent their own officers in the place of their mirror counterparts to gain information. Lieutenant Laura Horodyski replaced her mirror counterpart and obtained the information when the Empire was going to attack Earth. (Star Trek: Odyssey: "Dark Reflections"), (Star Trek: Odyssey: "Through Their Eyes")

The Empire made an attempt to use the Guardian of Forever to go back in time and kill Captain James T. Kirk but Captain Jermaine Allensworth thwarted their plan. (Star Trek: Odyssey: "Held in the Hands of Forever")

A brief battle between a small group of Imperial and Federation forces occurred at Saturn in an attempt from the Empire to rescue the Mirror Counselor Nycz, who had been taken prisoner by the Federation after she was found out. (Star Trek: Odyssey: "Through Their Eyes")

The Federation set up a defense around Earth and waited for the Empire to attack. Meanwhile, other Federation fleets at Deep Space Nine were en route to Earth but were attacked by Imperial forces, however, the Federation was able to fend off their attackers. The Terran Empire attacked Earth outnumbering the Federation forces. When the rest of the fleet arrived from Deep Space Nine, they were still outnumbered until Klingons and Romulan ships decloaked, giving the Federation the edge over the Empire. As the battle raged on, more Federation ships arrived, however, these ships came through a wormhole from the Mirror universe. A fleet of Federation ships were sent to the Mirror universe to attack the Mirror Earth and apprehend the Emperor and Empress. With the leaders of the Terran Empire in hand, the Terran Empire had no choice but to surrender. The Federation had won. (Star Trek: Odyssey: "Where Mortals Are Forbidden")


The war had officially ended with the signing of the Mirror Treaty. All Imperial forces returned to their own universe, except for the Emperor and Empress who had to stand trial for their war crimes. (Star Trek: Odyssey: "Dining on Ashes")

Timeline of known engagements[]

  • Battle of Talos
  • Battle of Betazed
  • Liberation of the Ba'ku
  • Terran Empire attack on Earth
  • Battle of Mirror Chin'toka
  • Battle of Cestus III
  • Battle of Saturn
  • Battle of Deep Space Nine
  • Invasion of Mirror Earth
  • Battle of Earth

Background information[]

Odyssey writer Rylan Sato wanted to bring back the Mirror Universe in a way that was different than what Deep Space Nine had done. "I wanted to go back to the original roots of the Mirror Universe and make it different than what Deep Space Nine did with it. I liked the Mirror episodes but I didn't want to root for the Terrans because they were the bad guys in a sense. We had no one to root for in the Mirror episode of Enterprise and we of course rooted for Kirk and his team in Mirror, Mirror. The Terran Empire could've had a lot of potential to work with, without causing them to fall to the Klingon-Cardassian Alliance. I used the idea from the Next Generation episode Parallels 'thinking what if there was another universe for the Mirror Universe, a universe where the Empire thrived and conquered everyone around them. It wasn't until after I had written Objects in the Rear View Mirror when I thought of having a war with the Empire. Why not have a war with yourself? Fighting with Klingons and Romulans is overused and the Cardassians are in no way, shape or form to fight a war with the Federation again, so I figure who else could hold a candle to the Federation in terms of strength, the Terran Empire."

Once asked about having the Mirror war take place less than a decade after the Dominion War, Sato also noted: "It's still reasonable. Hell, two years after the American Revolution, the United States fought against various Indian tribes for ten years for control over the Northwest Territory. Wars don't happen when you want them to, they usually happen when you least want them."

External link[]

Star Trek: Odyssey at