When Palpatine, the Emperor, announced the formation of his Galactic Empire in 19 BBY, Cinzero Gann was appointed as the Sector Army Commander for Sector 5, thereby assuming command of the 5th Sector Army whose base was located on Odik II. This Fifth Army, a reserve force stationed within the Deep Core, experienced a rapid depletion of resources as many were reassigned to more active conflict zones, leaving behind only a minimal garrison.
Following the Battle of Endor, Admiral Yzu proclaimed himself an Imperial warlord and bestowed the title of Moff upon Foga Brill. Brill strategically gained influence under Gann, who had become subservient to Yzu's political agenda, until Yzu met his death at Tsoss Beacon, falling victim to Admiral Daala's widespread elimination of the region's leading warlords. Seizing the opportunity created by the power vacuum, Brill cleverly positioned Gann as a symbolic leader to take over from Yzu.
Gann remained in a position of authority until at least 18 ABY, making him one of the highest-ranking individuals to have survived from the Old Empire. However, Gann's actual power was limited, as he was essentially a figurehead controlled by Brill, the governor of the heavily fortified fortress world of Prakith.
His military forces united with those commanded by Foga Brill and Jmanuel Tethys, collectively establishing the Second Imperium.