The Federation-Klingon Cold War, however, escalated around 2223 and lasted almost seventy years. (Star Trek VI: The Undiscovered Country) Key disputed regions included Sherman's Planet, Organia, Donatu V, Neural, Capella IV, the Archanis sector, and the Tellun system. (TOS: "The Trouble with Tribbles" , "Errand of Mercy" , "A Private Little War" , "Friday's Child" , "Elaan of Troyius" ; DS9: "Broken Link") In 2245, one of the most noted battles was the Battle of Donatu V in the area of Sherman's Planet. The results of that battle were inconclusive. (TOS: "The Trouble with Tribbles" )