The Siege of Manaan was a years-long campaign waged by the New Sith Imperium against the planet Manaan during the Third Galactic Civil War. The campaign began after the Empire was faced with a shortage of the healing substance known as bacta and decided to use the kolto on Manaan as a supplemental healing agent. The Empire quickly captured Ahto City, the only surface structure, but did not have the technology to mount an aquatic invasion. They developed this technology over the next two years, during which time the Alliance Remnant, led by former Jedi Master Kara Vaalki, joined with the native Selkath to defend the planet. The Empire invaded the oceans after two years, though Vaalki and her forces, which became known as Defiance Squadron, held out long enough for the Selkath, Quarren, and