The Battle of Borosk arose from Darth Krayt's revived military campaign spanning the galaxy. After the Sith Empire seized Borosk in an earlier conflict, control of the planet shifted repeatedly between Krayt and Fel. By the year 138 ABY, Fel loyalist forces had regained control of the world.
Nevertheless, the Bastion forces found themselves defeated when the Sith-Imperial army came back to reclaim the planet. Rand Ko, the Imperial Knight in charge of Fel's troops, was instructed to withdraw by his Emperor. As Roan Fel completed issuing these commands, the holocomm connection between Ko and Fel was abruptly severed. The final image Fel witnessed of his dedicated Imperial Knight was an assault by a Sith Lord.