War of the Primal Tide
During the events of the War of the Primal Tide, an unexpected alliance was signed. Against the forces of the Black Legion, the Phantom Prophets rose against the invasion of chaos, the possibilities indicated that chaos would be victorious until reinforcements from Bulcatus joined the battlefield, the combined forces of the chapters fought in unison and with such mastery that it was as if they had trained together for centuries. This campaign created a bond of alliance between both chapters that will be recorded in the annals of the Empire for ages to come.
