Great Scourge of Malachor

"It looks like at one time, thousands of years ago, Jedi Knights attacked the temple.''" "And the Jedi won, right?" "''From what I can tell, nobody won."

- Ezra Bridger and Ahsoka Tano

The Great Scourge of Malachor was a battle between the Jedi Order and the Sith on the planet Malachor. During the battle, the Jedi attacked the Sith temple, a battle station and superweapon capable of destroying life. The remains of the battle, in which combatants were left petrified, remained preserved for thousands of years after the Great Scourge.

History
"The ground looks scorched."

- Ezra Bridger, upon discovering the battlefield

Thousands of years before the Galactic Civil War, the Jedi Knight attacked the Sith temple on the planet Malachor. In the ensuing battle, the temple was activated, resulting in the death of everyone on the planet. The petrified bodies of the combatants were all that remained, left littered across the battlefield. The horrors of Malachor would go on to inform Jedi legends for millennia to come.

In the third year before the Battle of Yavin, the petrified remains of the battlefield were discovered by Padawan Ezra Bridger, Jedi Knight Kanan Jarrus, and the former Jedi Ahsoka Tano. Tano, remembering her Jedi teachings, recalled that a battle had been fought on Malachor. Bridger wondered if the Jedi had won, but Tano deduced from the remains of the battlefield, that nobody won. Bridger also found a green-bladed crossguard lightsaber, which he briefly activated before it shorted out. After Kanan was blinded by former Sith Lord Maul, he found a Jedi Temple Guard mask and wore it whilst briefely dueling with Maul

Behind the scenes
The Great Scourge of Malachor was first referenced in the 2015 reference book Star Wars: The Force Awakens: The Visual Dictionary, which stated that the crossguard design of Kylo Ren's lightsaber was an ancient one that dated back thousands of years to the Great Scourge of Malachor. The book's author, Lucasfilm Story Group creative executive Pablo Hidalgo, added the reference to the book to connect it with the battle that was ultimately referenced in "Twilight of the Apprentice," the second season finale of the animated television series Star Wars Rebels.

Although the exact events of the Great Scourge have yet to be revealed, Star Wars Rebels executive producer Dave Filoni shared his thinking for what the battle was. In his mind, the battle was fought when Jedi Knights attacked the Sith temple that was being constructed by a Sith Lord, the voice of whom became the Presence in the obelisk that is activated by the Sith holocron that Ezra finds in "Twilight of the Apprentice." In this idea, the temple either fired or misfired and led to the petrified destruction that remained on the battlefield for thousands of years. The episode's credits identify her only as "Presence."