Klingon - Cardassian War The Klingon - Cardassian War was a major interstellar conflict resulting from the the Klingon Empire invading the Cardassian Union , lasting from early 2372 to mid - 2373 . The war devastated the Cardassian state and paved the way for its absorption into the Dominion , ironically achieving what the Klingon invasion had sought to prevent . The manipulation of the Klingon s into launching an unprovoked attack on the Cardassians would prove to be one of the greatest coups of Changeling infiltration in the Alpha Quadrant . Revolution and paranoia . In 2372 , reports emerged through the sealed borders of the Cardassian Union that the Cardassian Central Command had been overthrown by a popular uprising , restoring power to the civilian Detapa Council . The growing strength of the Cardassian dissident movement , coupled with the loss of security due to the collapse of the Obsidian Order following the disastrous Battle of the Omarion Nebula , had at last been able to remove one of the most oppressive regimes in the Alpha Quadrant . On Qo ' noS , the news was received in a different light . Chancellor Gowron and the Klingon High Council became convinced that the revolt on Cardassia Prime was instigated by the Dominion and that the Detapa Council had been replaced by Founder s . One of the most influential officers in the Klingon Defense Force s , General , called for a massive invasion of Cardassian space to end the " Changeling threat " . Many Klingons , who had grown restless after decades of peace , rallied around him . They were unaware that Martok himself had been replaced by a Changeling , whose mission to weaken the Dominion ' s enemies was proceeding perfectly . Emperor condemned the invasion , to no effect . ( ) The invasion was to involve a third of the Klingon Empire ' s standing forces , with over a hundred ships in the first wave alone . The plan was to mount a lightning thrust into the heart of Cardassian territory and conquer the Cardassian homeworld . All governmental officials would be executed , and an imperial overseer installed to put down any further resistance . The advance task force of over fifty warships , led by Martok aboard the , was dispatched to Federation starbase Deep Space 9 under the guise of defending the station against a Dominion incursion . Preemptive invasion . Captain Benjamin Sisko , commander of Deep Space 9 , was suspicious of the Klingons ' motives as there had been no significant Dominion activity near the Bajoran wormhole for months . Thus , he ordered Lieutenant Commander Worf to uncover the Klingons ' true intentions . Once appraised of the planned invasion , Sisko urged Martok to call off the attack and informed him that the Federation would not support an unprovoked attack . Martok paid his warning no heed , and shortly after commenced the invasion . The Federation Council quickly condemned the invasion , and in response an enraged Gowron withdrew from the Khitomer Accords , ending the alliance between the Klingon Empire and the Federation . With Starfleet ordered not to interfere until the Federation Council could re - establish a dialog with Gowron , the Klingons were free to cross into Cardassian space . However , Elim Garak , aboard Deep Space 9 , was able to send warning to Legate Dukat , Chief Military Adviser to the Detapa Council . Although the outlying Cardassian colonies were overwhelmed almost immediately , the Cardassian fleet did mobilize in time to offer greater resistance as the Klingons pressed closer to Cardassia Prime . Nevertheless , the Klingons still broke through the Cardassian lines after a pitched battle , leaving them only 52 hours from Cardassia Prime . Realizing the planet could not hold , Sisko offered to shelter the Detapa Council aboard Deep Space 9 . Dukat evacuated the council members aboard the cruiser " Prakesh " , though they were intercepted by several Klingon warships . With a timely rescue from the , the Council members reached Deep Space 9 . With this development , the Klingon fleet turned away from Cardassia and attempted to take the council members from Deep Space 9 by force . Fortunately , the weapons of the station had been heavily augmented in anticipation of a Dominion invasion , and it was able to withstand the siege long enough for Starfleet reinforcements to arrive . Stalemate . Following their defeat at Deep Space 9 , the momentum of the Klingon invasion was blunted and Cardassia Prime was out of danger . Gowron , fearing assassination from his failure to conquer the Cardassians , simply declared victory and recalled his forces . Meanwhile , the Klingons , refusing to relinquish the colonies they had conquered , began fortifying their positions and deploying orbital defense system s in preparation for a longer war of attrition . ( ) In the following months , cloak ed Klingon warships continued to rampage throughout Cardassian space alone or in small groups , destroying targets of opportunity and plundering Cardassian shipping . The outmatched Cardassians responded with unconventional tactics such as sensor ghost s and holo - projection s , which earned the respect of some Klingons . ( , ) The Klingon attacks devastated the Cardassian infrastructure , resulting in a humanitarian crisis . Diseases once under control swept through Cardassian colonies , while the government struggled to even meet the basic needs of its people . With their fleet occupied , the Cardassians were forced to ask the Federation for assistance , such as in providing escort vessels for medical relief convoys responding to an epidemic of Rudellian plague in the Pentath system . The Federation also provided twelve CFI replicators to help rebuild Cardassian industries , though they were hijacked by Deep Space 9 ' s chief of Starfleet security , Lieutenant Commander Michael Eddington , who was secretly a member of the Maquis . The war had virtually granted the Maquis free reign in the Demilitarized Zone , as the Cardassians no longer had the resources to combat them . ( ) Despite their losses , the Detapa Council remained unwilling to lose what was left of its fleet and remained on the defensive , hoping for a diplomatic solution . After the destruction of the outpost on Korma , which also killed fifteen Bajoran delegates attending a conference , Gul Dukat and Major Kira Nerys managed to capture a Klingon Bird - of - Prey . Unable to convince the Council to go on the offensive with the trove of military intelligence provided by the Bird - of - Prey , Dukat decided to embark on a personal war with the Klingons . ( ) Cardassia joins the Dominion . As the war dragged on ineffectually into a second year , Gul Dukat entered secret negotiations for the Cardassians to join the Dominion , placing himself at the head of the new Cardassian government . In mid - 2373 , a massive Jem ' Hadar fleet of over fifty ships crossed the wormhole and entered Cardassian space . In only three days , they inflicted massive casualties on the Klingon forces . Gowron was forced to issue a general retreat , intending to fortify the Klingon Empire and prepare for a fight to the death . Instead , Sisko prevailed on him to revive the Khitomer Accords aboard Deep Space 9 and stand together with the Federation against the Dominion . After over a year of conflict , Klingon and Cardassian territories had returned to their pre - war state , only with the Klingon military substantially weakened , making the Dominion position that much stronger for the coming Dominion War . ( )