The Empire launched a two-pronged attack on Balmorra during the war, believing Balmorra's weapons production facilities and proximity to the Core Worlds to be of great strategic importance. The first prong of the attack involved slicing and reprogramming the networked security systems that guarded the planet's factories, lab facilities and weaponry‒in effect, turning Balmorra's defenses against itself.
The second prong was direct bombardment, aided by Balmorra's compromised orbital defense towers and satellites. This attack devastated the planet's primary military forces and central government, leaving a unified response nearly impossible.
Eventually, the Empire landed a full invasion force. By this time, the Republic had come to Balmorra's aid but was forced to abandon the planet with the Treaty of Coruscant‒after which, the Imperial military declared victory and established its headquarters in Sobrik. The Balmorran resistance proved more wily than the Empire anticipated, however, and Balmorra's factories proved difficult to control, leading to a years-long morass in which the Empire is still mired.