During the conflict known as the Great Galactic War, which pitted the Sith Empire against the Galactic Republic, a battle unfolded on the isolated planet of Ilum. This icy world, revered by the Jedi Order as a sacred place, became a strategic location for the Republic Military to launch unexpected offensives because its location was concealed and its hyperlanes were challenging to traverse. Despite an assault by the Sith, control of the planet remained with the Republic and the Jedi Order for a number of years following the Treaty of Coruscant in 3653 BBY.
The initial reference to a battle that occurred on Ilum during the Great Galactic War appeared within "The Setting" article, which was featured on the Star Wars: The Old Republic website in October of 2008. However, after the website underwent an update in June of 2011, any references to the battle, including the battle of Dathomir, were taken down.