The Second Battle of Belderone was a revenge operation lead by Darth Adsec two days after the Padawan Slaughter. By this time Jacen Solo had left Belderone to inform the Galactic Alliance that the conuter-attack had failed and was not present at the battle.
A Sith bombarder warship destroyed much of the planet's surface and killed most of the garrison on the planet before the Sith troops came in to eliminate the remaining Alliance and Jedi forces.