Having remained loyal during the Unification War, Cannis suffered little damage and developed a reputation as a vacation world for turians across the Hierarchy. During the Krogan Rebellions, it was seen by the krogan as a potential launching point for any assault on Palaven, and was subsequently conquered by Clan Dinroth in the First Battle of Cannis. Given its strategic value, Cannis was fortified heavily by the Dinroth, the clan moving almost all of their forces from Tuchanka to reinforce it.
The eventual turian counterattack, the Second Battle of Cannis, became one of the bloodiest of the entire Rebellion. Initially, both sides hoped to preserve the world’s infrastructure and environment for their own use. As such, traditional engagements were fought across the world’s surface with very little use of artillery or orbital weaponry. The Dinroth’s numerous fortified positions and hidden bunkers resulted in what has been compared unfavorably to Earth’s ‘trench warfare’, with hundreds of thousands of turian soldiers landing on the moon to face smaller but heavily-fortified krogan units. After several weeks of grinding assault, and with krogan reinforcements on the way, the turian General Trebonian ordered a withdrawal and bombarded the colony from orbit. Clan Dinroth would never recover their pre-war numbers, joining the myriad Tuchankan clans with no interest beyond their immediate survival.
Following the release of the genophage, Cannis was left uninhabited as a memorial to the dead of both sides. It has since become a popular destination for historical tourists, but remains minimally populated.