16. The Moorish Wars (534-548) between the Byzantine Empire and the local tribes of North Africa caused more than 5,000,000 deaths across a 15 year period
The praetorian prefecture of Africa was a region of the Eastern Roman Empire, conquered from the Vandals in 534; governed from Carthage, the new district almost immediately faced a rebellion from local Moorish tribes. Despite efficiently putting down this revolt, Solomon, the Magister Militum, faced a mutiny in the spring of 536, destabilizing the territory and allowing pockets of resistance to endure. Carthage was besieged by an army of 9,000, but was spared by the timely arrival of Belisarius from Sicily to relive the ancient city. Despite this reprieve, in 542 the Plague of Justinian would afflict the region, precipitating mass suffering and ferment further rebellion.
In 544, Soloman was killed in battle at Cillium and his armies routed. In the disruption, the Moors captured and sacked the coastal city of Hadrumentum and much of the rural areas of the prefecture fled to Sicily for safety. Eventually, after years of in-fighting, backstabbing, and chaos, Emperor Justinian sent John Troglita to restore order to the region. Despite commanding a numerically smaller force, John, a proficient general, rapidly made progress in reconquering the anarchic territory. In 547, John would emerge victorious at the Fields of Cato, defeating the combined forces of the Moors and rebellious Greeks, thus ending the fifteen-year revolt; this victory would be short-lived, with the Moors conquering the region in the 7th century.