The Battle of Mezlagob, nicknamed the "Unfought Battle", was the penultimate engagement of the Great Liberation. It saw the surrender of the Tetrarchy fleet and the capture of Mezlagob, the Tetrarchy's capital.
The Tetrarchy's economy was in shambles after the capture of Vall`to by the Golden Empire. The Vall`to Sector Bank had not only abandoned the Tetrum, but was actively backing the Royal Credit, which caused skyrocketing inflation and warned investors that the Bank saw little to no chance of the Tetrarchy recovering and winning the war. The Bank of Mezlagob backed the Tetrum, but lacked the reserves of wealth or economic credibility to stave off the inflation.
Admiral Garyth Quorr's death at Vall`to had wreaked havoc on morale among the Tetrarchy troops. The Tetrarchs themselves tried to assert greater day-to-day control over the military, and many troops balked, especially when they compared the politicians to Quorr, who had been a respected leader and skilled tactician. Confidence among the public was also waning; Telacia had surrendered without a fight, and the Empire's casual capture of Hudrel contrasted bitterly with the earlier Battle of Hudrel, which the Empire had fled in defeat. The dead Dronos Tetrarch Dourshe had been replaced by Catel Embri, but the Tetrachs had not even bothered to replace Pexereca Tainer when he was assassinated by Aquila Corcer. All these things combined to give the impression of a government in its last, desperate death throes.
Meanwhile, the Golden Empire was prospering, having achieved control over every Tetrarchy system in the Vall`to and Xoquon sectors. Some, including Hudrel, Baes, Vall`to, Tizgo V, and Dolomir had not welcomed the invaders and had some insurgent movements, but most former vassal worlds had rejoiced at their "liberation" and even some former full member worlds viewed the Empire's victory as an inevitability. With control over most of the Tetrarchy's planets secure, Queen Rin Sakaros felt the time had come for the final push to topple the Tetrarchy.
Knowing the Empire's assault was inevitable, Admiral Yman Ailad, appointed to replace Quorr, attempted to convince the Tetrarchs to bargain for terms of surrender. Incensed, they had him put to death for treason and appointed his Vice Admiral, Dithiar Minum, in command. Ailad and Minum had been close, and Minum, already wearied by war, became embittered as well.
The Prime Fleet decanted from hyperspace, with the Sith Star in the lead and all four of its Imperial Star Destroyers present. The Tetrarchs were aboard their flagship, the Cleansing Wave, and initially rebuffed Rin's invitation for the fleet to surrender. But before they could initiate battle, a Tetrarchy captain cut in to surrender his ship. Lahek Gril called him a traitor and commanded his fleet to open fire on the ship in question, but three more ships offered surrender instead. While Rin and her brother Tariun watched in bemusement, more and more of the ships powered down their weapons, until Vice Admiral Minum seized his ship's transceiver from the Tetrarchs and offered the surrender of the entire fleet.
The Tetrarchy ships were boarded without issue and their crews taken prisoner. As a condition of accepting the surrender, Tariun ordered that the Tetrarchs be handed over to his forces alive. Lahek Gril committed suicide rather than face Rin, but the crew of the flagship seized the astonished Mezzels and restrained them, presenting them to the boarding crews moments later. Mezlagob itself surrendered its planetary defenses, and the ship crews gave up the codes to disable the system's battle droids. Vice Admiral Minum was taken into Royal custody for a year, but eventually released to house arrest, and ultimately pardoned entirely in 126 ABY.
In the week following the surrender, live on the Royal HoloNet, Rin pronounced the two remaining Tetrarchs guilty of crimes against sentients and executed them personally. With Mezlagob in the hands of the Empire, most of the remaining Tetrarchy worlds contacted the Empire with their voluntary surrenders. Ommol, however, adamantly refused to concede, leading to the Battle of Ommol.