United Federation of Planets vs. Klingon Empire
Additional Powers:  
  Casualties: Unknown, presumably many.


A Klingon fleet heads toward Deep Space Nine


The Second Federation-Klingon War was a brief but brutal conflict fought between the United Federation of Planets and the Klingon Empire from 2372-2373. The war began when Chancellor Gowron, instigated by a Founder posing as his trusted aide Martok, issued an ultimatum demanding the cession of several Federation border territories that had been claimed by the Empire a century previously, most notably the Archanis sector.

In the ensuing fighting, the Federation proved almost completely unprepared for a sustained conflict on the 'secure' Klingon border, with few assets in the way of the Klingon war machine despite the developing tensions that had begun with the Klingons' withdrawal from the Khitomer Accords at the beginning of the year. Several dozen starships and border worlds were attacked during the fighting across a wide swath of territory from Archanis all the way to the Bajor sector. Over time however, it is implied by the Martok Changeling that the Federation managed to rally and start to slow the Klingon advance down with steadily increasing proportions of losses to the Klingon Defense fleet, a fact that would haunt them when the Dominion finally entered the Alpha Quadrant.

Acting on information provided by Odo, who had recently been in the Great Link, the Federation became convinced that Gowron had been replaced by a Founder, who was fighting the war to weaken the two former allies pending a full invasion. A covert operations team, led by Captain Benjamin Sisko, infiltrated the Klingon military headquarters on Ty'Gokor with the intention of exposing the Gowron changeling. However, it was ultimately revealed that Martok, not Gowron, was the real shapeshifter, and that Odo's information had merely been planted in the hopes of further worsening Federation-Klingon relations. For the service of exposing the enemy spy, Captain Sisko's team was allowed to leave Klingon space unhindered, and Gowron convinced the Klingon High Council to call for a cease-fire.

The ceasefire was broken briefly a few weeks later, when Klingon troops attacked Ajilon Prime. It was quickly reinstated. Hostilities were only completely ended when Chancellor Gowron agreed to re-sign the Khitomer Accords in the face of the Dominion invasion six months later.