Sul-34, a Navigation Buoy, functioned as a hyperjump point.
Prior to the Battle of Endor, several Rebel starships utilized it to meet up with the Alliance Fleet close to Sullust. Darth Vader dispatched Maarek Stele to command a squadron of Missile Boats, protected by Assault Gunboat escorts, in order to ambush and eliminate the initial three Rebel capital ships that arrived. The purpose of this was to weaken the Rebel forces and postpone their attack while awaiting reinforcements.