Second Battle of Chin'toka
The Second Battle of Chin'toka was a major battle between the Federation Alliance and the Breen-Dominion Alliance during 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 United Federation of Planets, Klingon Empire and Romulan Star Empire. 

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 and left only the Klingon able to counter the Dominion, the Dominion could not follow up on their victory, as the Cardassian Rebellion occurred shortly thereafter, diverting vital Dominion resources from the front-lines. This proved catastrophic when it caused a Jem'Hadar fighter equipped with an energy-dampening weapon to fall into Alliance hands, allowing Federation and Romulan ships to counter the weapon.

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 suits, 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 years – with their original plans having projected the invasion of the Federation and the Klingon Empire to only take six months 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 Forces. 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 shields 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 pods 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 Allied 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 formation of the Cardassian Liberation Front, 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. ()

External link
 

bg:Втора битка за Чин'тока
de:Dritte Schlacht von Chin'toka
ja:第二次チントカ星系の戦い
nl:Tweede slag om Chin'toka
Chin'toka, Second Battle of