The Mandalorian Civil War began in the capital city of Sundari when the Shadow Collective removed Duchess Satine Kryze and her New Mandalorian administration from power. To decide who would rule Mandalore, Maul challenged Pre Vizsla, the leader of Death Watch, to a battle for leadership. Although Maul was victorious, killing Vizsla in combat, not all Death Watch members accepted this change in leadership. Bo-Katan Kryze, the Duchess' sister and loyal to Vizsla, transformed her forces into the Mandalore resistance and revolted against Maul's reign, which caused the conflict. Obi-Wan Kenobi took part in the Battle of Mandalore, as did Darth Sidious, who engaged Maul and his brother, Savage Opress, in combat. During the battle, Darth Sidious killed Savage, and Maul was captured by the Sith Lord and imprisoned in the Spire located on Stygeon Prime.
Despite efforts by Prime Minister Almec to discredit former Duchess Satine Kryze by falsely accusing her of abandoning her pacifist ideals to murder Vizsla, thus concealing Maul's actions, Satine Kryze's execution at Maul's hands ignited a rebellion among many Mandalorians. These Mandalorians united with the goal of liberating Mandalore from the outsider who had seized control of its throne. Even as the civil war continued to rage across Mandalore, Maul was freed by his Mandalorian super commandos, but his mother, the powerful Nightsister Talzin, was killed during the Second Battle of Dathomir shortly thereafter. Maul went back to Mandalore, but the Galactic Republic and the Mandalore resistance besieged the planet. Maul was apprehended, and Kryze gained control of the planet. Ultimately, however, she lost her authority when she refused to submit to the Galactic Empire, which initiated an occupation of Mandalore using the clone forces that were still present.