In "Hero Worship" it is mentioned that they have always been politically nonaligned. They later become a powerful ally of the Dominion, a Gamma Quadrant empire, during the Dominion War that was fought during the final two seasons of "Deep Space Nine". The Breen were revealed to have allied with the Dominion in "’Til Death Do Us Part", the second episode of the nine-episode story arc that served as the final story arc of "Deep Space Nine" in 1999. After this occurred, the Breen attacked Earth, destroying parts of San Francisco before being repulsed. They also proved a powerful foe during the Battle of Chin'toka, in which they fought alongside the Cardassians and Dominion against an alliance of the Federation, the Klingon Empire and the Romulan Star Empire. During this battle, the Breen helped destroy a fleet of the alliance's ships, including the USS "Defiant". The Breen also assumed great responsibility in military matters. The leading representatives of the Breen Confederacy, called "Thots" (which , leader of the Cardassian military, compares to his own rank of Legate, in the episode “”), such as Thot Gor and Thot Pran, were given more powers, much to the bitterness of Damar, whose own people had earlier joined the Dominion. This was one of the factors which led to Damar changing sides and leading a rebellion to free Cardassia. After the Cardassians turned against the Dominion, the Dominion and the Breen were defeated in the Battle of Cardassia Prime in "Deep Space Nine's" series finale, "What You Leave Behind". The Breen's status with respect to the Dominion after this has not been mentioned onscreen since "What You Leave Behind", and is therefore unknown in canon.