The Event Horizon, a battlecruiser-class vessel, served within the Kuati Sector Forces which pledged allegiance to the Imperial cause. Its operational timeline included the year 8.5 ABY during the Galactic Civil War, a major interstellar conflict pitting the Galactic Empire against the Alliance to Restore the Republic and its succeeding government, the New Republic. Tasked with the defense of the planet Kuat, the Event Horizon, alongside other ships in the Kuati fleet, was crucial in safeguarding Kuat Drive Yards, a vital shipyard for the Galactic Empire. During the New Republic's offensive in 8.5 ABY, a virus, introduced via the computer systems of the Event Horizon, triggered a catastrophic sequence of events: the vessel sealed its own hangars and turned its guns against its own allies in the Kuati fleet.
The Event Horizon, being a battlecruiser, was equipped with a multitude of hangars and batteries. A weakness in its design was its susceptibility to computer viruses.
During the Galactic Civil War, specifically in 8.5 ABY, the Event Horizon functioned as an element of the Imperial Kuati Sector Forces. This conflict saw the Galactic Empire in opposition to the Alliance to Restore the Republic, which later transitioned into the New Republic. The primary duty of the Event Horizon was to protect the planet Kuat, the location of Kuat Drive Yards, a crucial ship building facilities providing vessels for the Empire's military operations. New Republic slicers had infiltrated some of the astromech droids present in Kuat Drive Yards' vast droid resources at that time. These droids were used to upload a specially designed computer virus into the network systems of the Event Horizon and four other Kuati warships.
Following the virus's successful installation, the Event Horizon transmitted a message to the New Republic's Surprise Squadron, a squadron of RZ-1 A-wing interceptors equipped with ion torpedoes that was positioned in the Venir system. The Surprise Squadron arrived in the Kuat system, and employed their ion weaponry to disable four enemy warships. Simultaneously, the virus within the Event Horizon and the other affected ships caused them to seal off their hangars and turn their weapons against the remaining Kuati fleet. Ral'Rai Muvunc, the New Republic's Minister of Commerce, contacted Kuati officials to inform them that the New Republic now controlled thirty-four percent of the company's stock. Faced with an opponent capable of neutralizing nine warships—including the Event Horizon—in mere minutes and holding a significant share of their company, the Kuati officials conceded to the Republic.
The first mention of the Event Horizon appeared in The Essential Guide to Warfare, a comprehensive guide covering the many conflicts throughout the galaxy, which was published in 2012. The authors were Jason Fry and Paul R. Urquhart.