During the initial months of the Imperial Era, a rebellious movement arose on the Expansion Region world of Umbara, a planet which had significantly backed the Confederacy of Independent Systems during the Clone Wars – a conflict between the Confederacy and the Galactic Republic, which was the Empire's forerunner. In the year 19 BBY, this resistance mounted a significant military challenge against the forces of the Imperial Military.
Lieutenant Commander Orson Callan Krennic informed the Erso family, a group of scientists, that the Empire viewed the Umbara uprising as a consequence stemming from the Clone Wars. Krennic asserted that the Empire's actions against this rebellion, alongside other emerging resistance factions of that era, were simply part of a pacification effort. Although the resistance fought for Umbara, the Empire ultimately seized control of the planet.
The Umbara resistance was referenced within Catalyst: A Rogue One Novel, a novel published in 2016 and authored by James Luceno.