Attack on Jabba's Palace

In 20 BBY, the underworld conglomerate known as the Shadow Collective, under the command of the disgraced Sith Lord, Darth Maul, attacked Jabba's Palace on Tatooine in order to force Jabba the Hutt, a prominent member of the Hutt Grand Council, into cooperation with the Shadow Collective.

A junction between the criminal organizations of Black Sun, Death Watch, and the spice mining Pykes, the bulk of the attack was conducted by Mandalorian super commandos of the Death Watch, who attacked the perimeter of the Palace, paving the path for Darth Maul, Savage Opress, and Death Watch leader Pre Vizsla into Jabba's inner sanctum. After a very brief and violent struggle proving the Shadow Collective to be the more formidable, Jabba agreed to surrender his criminal empire, channeling his resources to the organization's cause for an imminent takeover of the Mandalorian capital city, Sundari.

Text and facts from the “Attack on Jabba's Palace/Legends” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.