The Battle of Byss was a battle in the Dark Order War, which resulted in the destruction of the Imperial factory ship Infector, and with it the campaign Operation Dark Disease was ended due to the destruction of the factory ship Infector, along with its escorting fleet.
During the Dark Order War, the fleet of Imperial warlord Jaden Korr spread fear throughout the galaxy with the deployment of dark troopers on New Republic planets in conjunction with a terror campaign known as Operation Dark Disease. Millions of civilians were killed in the first two attacks on Coruscant and Taris, subjecting the Republic to internal political pressure. In the First Battle of Bakura, however, Republic forces managed to steal information on the location of the Imperial factory ship Infector, on which the Operation relied in order to successfully deploy its battle droids on target worlds. As the Republic discovered, the Infector was scheduled to rendezvous with a freighter of resources and supplies near Byss. In order to end Operation Dark Disease before it could progress any further, Supreme Commander Dagmar Morlev personally led an armada to ambush and destroy the Infector at Byss.
The Republic fleet had been waiting for the Infector and its escorting fleet, utilizing six Immobilizer 418 cruisers to trap Imperial forces there. As expected, the Immobilizers' gravity well projectors forced the Imperial fleet out of hyperspace, where they were immediately taken by surprise. All Republic fighters and bombers had been launched in advance, which gave them an immediate advantage as they attacked the forward group of Tartan cruisers and Victory-class Star Destroyers.
The Calamari Cruisers largely outnumbered and outmatched the Victory-class destroyers. Despite tenacious resistance from the Imperial-class Star Destroyers, they would not be able be able to hold the Republic vessels for long. The forward assault of MC80 Star Cruisers was led by Dagmar Morlev's flagship, the Mandate of the People. While the Imperial fleet launched Assault Gunboats and V38 Assault Fighters, the Republic's five Defender-class Star Destroyers broke off from the rest of the fleet and attacked the port side of the Imperial armada, eliminating several of their Tartan cruisers and Victory-class destroyers.
The Assault Gunboats initially held off Republic corvettes and X-wing starfighters with their concussion missiles, but the second wave of A-wings overwhelmed and pushed them back. The Imperial ships bolstered their front defenses with additional Tartan cruisers, and their port Star Destroyers returned fire at the capital ships. Hoping to buy time, the V38 fighters flew cover for Assault Gunboats, who bombed the Republic's front capital ships. Additional cover was provided by missile barrages from the Broadside-class cruisers, which claimed several groups of A-wings and E-wing fighters.
Despite the loss of two MC80 Cruisers, the Republic fought back against the assaults and forced their way through. To prevent further bombardment from the Broadside cruisers, A-wings led by General Wedge Antilles attacked and destroyed several of them with their concussion missiles and returned with medium losses. Dagmar Morlev then utilized a combat maneuver known as the Ackbar Slash, which consisted of forcing a fleet into the middle of an enemy formation, making the enemy ships reluctant to fire for fear of hitting allied ships.
The tactic worked, and the Imperial fleet was subsequently shattered. Their Gunboats and V38s were unable to combat the far more powerful and effective Republic fighters. After the ensuing bombardment from turbolaser fire and bombing runs, the only Imperial ships left were a handful damaged of corvettes and Star Destroyers, the Torpedo Sphere, and the Infector. Three Liberty-class cruisers moved ahead to engage the sphere, and subsequently took heavy damage from proton torpedoes. Morlev ordered an Alpha Strike, wherein all fleet vessels concentrate on the single target. Despite sustaining heavy bombardment, the sphere inflicted heavy losses on the capital ships and its shields were strong enough to withstand the Republic attacks for a time.
Meanwhile, the Infector, which was positioned behind the sphere, left its position and headed at full speed toward the closest Interdictor cruiser. Before anything could be done, the behemoth rammed through the ship, shattering its hull apart. To prevent the loss of their Interdictors, the Republic's Defender-class Star Destroyers and remaining X-wings broke off from the fleet to pursue the vessel. The Infector possessed a heavy anti-capital ship armament as well as powerful deflector shields, and the Republic capital ships were unable to slow it down. In its flight, the factory ship managed to destroy two more Interdictors. By this time, the torpedo sphere's shields had failed down and it began to lose power to its weapon systems. Dagmar's fleet concentrated on the torpedo tubes on the sphere's equator, eliminating most of its torpedo launchers. Several Defiance-class cruisers then moved to assist in the attack on the Infector. The Torpedo Sphere was then ripped apart by sustained fire from the other capital ships.
The last Interdictor, pursued by the Infector, diverted all power to its gravity projectors and engines, allowing it to outrun the Imperial factory ship, which then simply tried to flee out of the gravity projectors' range. Meanwhile, the entire Republic fleet was able to focus its fire on the factory ship. Although the vessel was outmatched, it managed to destroy four Republic capital ships before its shields failed. Unable to defend itself effectively against the Republic fighters and bombers, its engines were soon destroyed, and it was crippled. To ensure that nothing could be salvaged, Morlev ordered the fleet to continue firing until there was nothing left but a debris field.
When the battle began, the automated freighter IPF-07 shut its engines down after arriving, awaiting boarding for the transfer of its cargo. After the Infector was destroyed, one of the Republic Star Destroyers tractored it into its hangar bay, and the fleet left the area, returning to Republic space.
The Infector and its entire escorting fleet had been destroyed, effectively putting an end to Operation Dark Disease. As a result, the panic on Core, Outer, and Mid rim worlds ended. Even as the galaxy mourned the lives lost on Coruscant and Taris, morale throughout the Republic fleet soared with the reinforcement that the Dark Order could be defeated. Meanwhile, Jaden Korr's underlings lost even more faith in him than before, significantly reducing his already weakened control on the Order. This increased the confidence of Darth Persia, who eventually decided to accelerate his plans to overthrow Jaden's rule.