The Battle of Korriban, also known as the Invasion of Korriban or Operation Unity (because of the multiple Clone battalions fighting alongside each other) was a battle that took place during the Clone Wars, but was not part of the confllict, between the Jedi and Republic against a faction of Dark-side-users named the Grand Sith Order. Bloody and afterward secretive, the existence of the Sith and the mission were kept secret after the battle, and even Darth Vader himself never discovered of the battle's existence.