The Battle of Harrsk's fortress was a skirmish in the Imperial Civil War.
Admiral Daala.
Upon learning that Admiral Daala would be visiting the world of his nemesis, Supreme Warlord Blitzer Harrsk, High Admiral Treuten Teradoc sent his Crimson Command on a mission to humiliate Harrsk.
Just as Harrsk was showing off his assembled fleet of Imperial-class Star Destroyers to Daala, the Crimson Command force arrived in-system under the command of Vice Admiral Gilad Pellaeon, with orders to destroy Harrsk's prized flagship, the Shockwave.
Vice Admiral Pellaeon.
Commander Kratas, Daala's second-in-command, was touring the Shockwave and assumed command of the counterattack. Concentrating firepower on the large ship, Pellaeon's forces managed to overpower its shields and destroy it, damaging three other ships at the cost of eleven of their own.
In response, Harrsk forced Admiral Daala into his service, and the two took the remaining eight star destroyers to Teradoc's sphere of influence but the strike was prematurely stopped by the intervention of Daala. This led to the series of events which culminated in the warlord meeting at Tsoss Beacon and the unification of the Imperial Remnant under Admiral Daala and Vice Admiral Pellaeon.
The Essential Atlas identified Harrsk's capital world as Kalist.