ca 24,500 BBY

The First Great Schism between the followers of the dark and light sides of the Force occurs. A rogue Jedi named Xendor sparks the conflict after turning to the Dark Side and gaining many followers. Calling themselves the Legions of Lettow, they form a massive space fleet and declare war on the Jedi.
The New Essential Chronology; The New Essential Guide to Characters, Star Wars Gamer: "The Emperor's Pawns".
 
 
The Dark Jedi General Xendor is killed. Arden Lyn, Xendor's lover, is put into a death-like state by Jedi Master Awdrysta Pina, using the technique of Monichro. She will eventually reawaken after thousands of years.
The New Essential Chronology; Star Wars Gamer: "The Emperor's Pawns".
 
 
After a lengthy war, the Legions of Lettow are defeated, ending the first Great Schism.
The New Essential Chronology.