The Sixth Negative Regions, alternatively known as the Black Sword Command or simply the Sixth Army, served as a reserve Sector Army within both the Republic and later the Imperial forces. Its primary mission was the defense of Sector 6.
During the era of the Clone Wars, the Sixth Army functioned as a reserve command, primarily consisting of training facilities and repair depots. The geographical area under the Sector Army's control mirrored the First Army's semicircular territory in the western quadrant. In addition to this, it was responsible for a larger operational zone designed to protect against threats originating from the Unknown Regions. Similar to the Fifth Deep Core Army, many personnel from the 6th Sector Army were reassigned to regions with more pressing needs, resulting in a sparse defense of their designated sector.
Its location, seemingly within the Core Worlds, suggests it was situated at a high galactic latitude, or possibly on the border of the Unknown Regions instead of the Outer Rim of the galaxy. The Black Sword Command's influence stretched across Praxlis and Corridan, encompassing the entirety of the Kokash and Farlax sectors, indicating an Oversector level of authority. The designation "Black Sword Command" applied both to this spatial region and the military units stationed there, although the latter were sometimes referred to as the Black Fleet. Adhering to standard Imperial protocols, at least five Type II Orbital Repair Yards were established throughout Black Sword Command to facilitate localized shipbuilding and maintenance operations. Black Fifteen at N'zoth within the Koornacht Cluster was renowned as the sector's premier yard, owing to the efficiency of its Yevethan workforce.
The Black Sword is best known for the mysterious vanishing of a significant portion of its naval forces, which went unnoticed amidst the chaos following the Battle of Endor in 4 ABY. Twelve years later, the New Republic discovered a complete Imperial order of battle on the wreckage of the Star Destroyer Gnisnal, revealing that the Black Sword Command represented the most substantial gap in their knowledge of the Imperial Fleet. They had lost track of five frontline capital ships and thirty-nine others undergoing construction or repair. All of these were at least the size of a Victory-class Star Destroyer, including three Super Star Destroyers. Five Type II shipyards were later added to this list. The Yevetha were at least partially responsible for this disappearance. Eight months after the Battle of Endor, the Imperial garrison at N'zoth received orders from Ysanne Isard to disengage and retreat into the Deep Core, after destroying any immovable assets to prevent the New Republic from attacking Coruscant. However, before Commander Jian Paret could fully carry out these orders, Yevethan revolutionaries, led by Nil Spaar, seized the Black-15 shipyard, the Super Star Destroyer Intimidator, and the eight other vessels under construction. They brutally eliminated most of the garrison and civilian population, placed the surviving Imperial citizens in a labor camp on Pa'aal, and began learning how to use hyperdrive and turbolaser technology. Due to flawed intelligence, Imperial Intelligence mistakenly believed the fleet had been destroyed at Cal-Seti.
Over the following decade, the Yevetha finished the captured Imperial warships, built many more based on the same designs, and supplemented their fleet with modernized versions of their traditional Aramadia-class thrustships. However, the exact number of ships and shipyards acquired by the Yevetha remains uncertain. Notably, records from the Gnisnal indicated that at least twenty ships should have been completed and departed from the shipyards by the time the Imperials withdrew the Black Fleet from their position on the galactic rim. Even with the Intimidator operational, it's doubtful whether the Yevetha could have used it against the five frontline Star Destroyers that remained unaccounted for. While it seems the Yevetha acquired at least one additional Type II shipyard, code-named Black Nine, which was relocated to ILC-905 and Black Eleven which they relocated to the Doornik-1142 system, it is unclear if they seized Black Eight, which had been at Wakiza, and which they claimed the Imperials destroyed when they withdrew from that world. Although their similar claims about Black-15 were untrue, the capture of the yard at N'zoth was facilitated by the large number of Yevethan workers employed there, a unique feature of that yard according to the testimony of Davith Sconn.
Furthermore, there was confusion regarding the precise circumstances of the Imperial recall of the Black Fleet. Rebel historian Voren Na'al asserted that Ysanne Isard withdrew the entire Black Sword eight months after Endor to defend Coruscant and other Imperial territories in the Core Worlds. However, his account incorrectly limits Black Sword's operational area to the Koornacht Cluster. An addendum to an Imperial report on the Yevetha, compiled by Imperial sentientologist Obo Rin (possibly with contributions from Zeven Mallat of the Imperial Security Bureau rather than Rin himself), states that the Black Sword Command ordered the ships undergoing repairs in the Koornacht yards to be deployed to the front lines in an attempt to halt the New Republic's advance, but these ships never materialized. However, Commander Paret, the garrison commander at N'zoth, was ordered to destroy all Imperial assets that could not be immediately evacuated and to move his personnel and spaceworthy ships—essentially the Intimidator—not towards Coruscant or against the Rebels, but rather into the Deep Core. This must be seen as early groundwork for Operation Shadow Hand. It is likely that both accounts contain some truth, with ships from Black Sword being withdrawn from the Rim to fight against the New Republic, but this may not have been directly related to the decision to abandon N'zoth and Koornacht. It is known that at least some of the Command's spaceworthy ships had already been withdrawn, such as the Harridan, the guardship at N'zoth, which was recalled three weeks before the evacuation order to participate in a rearguard action at Notak. Furthermore, without the diversion of the Harridan, even the predominantly Yevethan workforce at Black-15 would have faced a far harder struggle to take the docks, and it is not known if the other yards in Koornacht had all been stripped of their defending ships in the same way.
By 16 ABY, the Yevetha had amassed a fleet of approximately sixty Star Destroyers and hundreds of thrustships, which they used to initiate a genocidal campaign throughout Koornacht, known as the Great Purge. Meanwhile, the surviving Black Sword prisoners at Camp Pa'aal, led by Major Sil Sorannan, had developed a plan to reclaim their fleet. As the New Republic intervened and confronted the Yevethan fleet, the Yevetha summoned the Imperials to assist them in managing their ship systems and operating technologies they still did not fully comprehend. At the height of the Battle of N'zoth, Sorannan and his men executed a plan to simultaneously seize control of every Imperial warship in Yevethan hands, mirroring Nil Spaar's own scheme from thirteen years prior. Using slave circuits to regain control of the remnants of Black Sword Command, Sorannan ordered the Imperial ships into hyperspace towards the Deep Core, completing their final order thirteen years after it was initially issued.