After overrunning nine Hive Worlds, Zanzag's Boyz would launch the famous Assault on Black Reach. By this point, the 2nd company of the Ultramarines under Captain Cato Sicarius had arrived in the Sector and realized that the key to the defeat of Zanzag's Waaagh! was to eliminate the warlord himself. Zanzag cleverly hid his base of operations in a cavern beneath a waterfall, initially avoiding any detection. However in the end the Ultramarines found his position after pursuing an Ork submarine. Captain Sicarius and Terminators of the Ultramarines 1st Company landed directly in the cavern and did battle with the Warboss himself. After many hours of combat, Zanzag was finally struck down and his Waaagh! soon fell into disarray afterwards.