Second Battle of Chin ' toka The Second Battle of Chin ' toka marked the entry of the Breen Confederacy into the Dominion War in late - 2375 , in a counter - attack against the Chin ' toka system , a territory of the Cardassian Union held by the forces of the Federation Alliance . Aided by the energy - dampening weapon of the Breen warships , the Dominion inflicted the worst major tactical defeat upon the Federation Alliance ; all but one of the 312 allied ships were destroyed in a rapid , but vicious engagement . Though the defeat stunned the Federation Alliance , the Dominion could not follow up on their victory , as the Cardassian Rebellion occurred shortly thereafter , diverting vital Dominion resources from the front - lines . Prelude . The Federation had made contact with the Breen in the mid - 2360s , though very little solid information was known about them even a decade hence . Isolated behind their full - body refrigeration suit s , they remained shrouded in mystery , a mystery that was only enhanced by their isolationist policies . As a result , the governments of the Alpha Quadrant considered the Breen to be little more than a minor regional power . By the second half of 2375 , the Dominion was faced with the prospect of the war dragging on for several more year s – with their original plans having projected the invasion of the Federation and the Klingon Empire to only take six month s at most . The Female Changeling , suffering the degenerative effects of the morphogenic virus , sought additional allies to swell the Dominion ' s numbers and bring about a quicker end to the conflict . After their initial contact , the Breen eagerly agreed to join the war on the side of the Dominion . ( ) The Chin ' toka system was the chief allied foothold in Dominion territory at the time , taken during a previous battle against the Cardassian and Jem ' Hadar forces . But the Alliance ' s weakened supply line and its fragile war machine meant its hold on the system was problematic at best ; Jem ' Hadar forces were constantly attacking the Alliance ' s positions , and with the Alliance ' s inferior numbers , its hold on the system was tenuous . ( ) Within days of their alliance with the Dominion , the Breen launched a massive offensive against Federation territories , including a bold attack against Starfleet Headquarters on Earth – the first time open combat had taken place on the planet in over two hundred years . ( ) The Dominion was resolved to re - take Chin ' toka with a combined assault of Breen , Jem ' Hadar , and Cardassian forces . With the bulk of the Dominion ' s forces already engaged on the Romulan front , the Breen would play the most important part in re - taking the system . The Battle . The Dominion forces managed to break through the Allied lines in two places at Chin ' toka , outflanking allied defenses . The Dominion fleet re - took the planets in the system , as the allied fleet withdrew . The Jem ' Hadar , Cardassian , and Breen ships consolidated their position while Starfleet and its allies rallied their starships for a counterattack to drive the enemy fleet from the system , under the command of General Martok of the Klingon Defense Force s . A total of 312 allied warships were rallied to take on the Dominion fleet . The Allied fleet charged into the system , resolved to destroy the enemy with brute force . As the Allied fleet entered the system , they destroyed several Breen warships . The Breen retaliated by firing a volley of a new kind of energy weapon , which , to the Allies ' shock , completely disabled all of their ships ' primary systems . The allies were now adrift and easy targets with their deflector shield s inactive , primary computer systems offline , and their weapons disabled . The Breen ships switched to conventional weapons , and targeted the now defenseless Alliance fleet with their torpedoes . The entire allied fleet was totally vulnerable , unable to even take evasive action or fire back . Ship after ship was destroyed or rendered uninhabitable after volleys of destructive torpedo fire . Unable to retaliate , the survivors aboard the heavily damaged allied ships launched their escape pod s in a desperate bid to flee the carnage . The Dominion leadership allowed the pods to escape , believing that the survivors would spread fear throughout the Alliance with tales of the destruction at Chin ' toka . With the allies warships destroyed , the Dominion re - took the system . ( ) Aftermath . The Second Battle of Chin ' toka was arguably the worst defeat suffered by the Allies throughout the war . In terms of starships lost to ships engaged , it was the worst defeat since the Federation ' s reversal in the Tyra system , in which 98 ships were destroyed out of 112 . The battle ended all allied offensives against the Dominion for the next month , while allied engineers scrambled to develop a countermeasure . The , a Klingon Bird - of - Prey , was the only allied ship impervious to the Breen ' s energy dampening weapons , thanks to a chance modification made by its chief engineer . The entire Klingon fleet made the same enhancements , making them the only allied ships resistant to the Breen ' s weapons . The Federation and Romulan fleets , however , were left vulnerable , leading to them being temporarily withdrawn from the front lines . General Martok brought 1 , 500 Klingon ships up to the front to fight the war while the Allies found a countermeasure ; however they were pitted against no less than 30 , 000 Jem ' Hadar , Cardassian , and Breen warships , outnumbered twenty to one . ( ) The Alliance was given precious time to develop a countermeasure due to the outbreak of the Cardassian Rebellion , led by Legate Damar . Its first assault on the Dominion ' s Vorta cloning facility on Rondac III caused the Dominion to re - focus its offensive energies to defeating the rebellion , costing them the opportunity of launching an offensive into Allied territory . This bought the allies enough time to develop a countermeasure with help from Damar ' s resistance cell , though the rebellion was all but annihilated when the Dominion destroyed eighteen Cardassian bases . The Allied fleets , now resistant to the main advantage the Dominion had , were able to organize their forces for a single , destructive blow to the Dominion at the Battle of Cardassia two months later . ( )