See Gothic War (376-382) for the war on the Danube.The Gothic War was a war fought in Italy and the adjoining regions of Dalmatia, Sardinia, Sicily and Corsica from 535 until 554 between the forces of the Eastern Roman Empire and the forces of the Ostrogothic Kingdom of Italy. It is commonly divided in two phases, the first (535-540) which ended with the fall of Ravenna and the apparent conquest of Italy by the Romans, and the second phase (540/541-553), where the Gothic resistance was reinvigorated under Totila and was put down only after long struggle by Narses, who also defeated the Frankish-Alamannic invasion of 554. However, various cities in northern Italy continued to hold out until the early 560s.
The war had its roots in the ambition of Roman Emperor Justinian to recover the provinces of the former Western Roman Empire, which had been lost to invading barbarian tribes during the previous century (see also Migration Period). The long duration of the conflict meant that by its end Italy was devastated and depopulated with the Italian population dropping from 7 million to 2.5 million as a consequence of war, famine and epidemics and the Eastern Empire's resources depleted. Thus the victorious East Romans were unable to resist the invasion of the Lombards in 568, which led to the loss of large parts of the Italian peninsula.
In 476, the Western Roman Empire in Italy was overthrown, when Odoacer deposed Emperor Romulus Augustulus and declared himself rex Italiae ("King of Italy"). Although he recognized the nominal suzerainty of the Eastern Emperor, Zeno, his independent policies and increasing strength made him a threat to the eyes of Constantinople. At that time, the Ostrogoths, under their leader, Theodoric, were settled as foederati of the Empire in the western Balkans, but were also growing restless. Zeno decided to "kill two birds with one stone", and sent the Ostrogoths to Italy to remove Odoacer, officially acting as the representatives of the Empire. Theodoric and the Goths were able to defeat Odoacer, and Italy came under Gothic rule. However, as per the arrangement between Theodoric, Zeno and the latter's successor Anastasius, the land and its people were regarded as still being part of the Empire, with Theodoric fulfilling merely the role of a viceroy and head of the army (magister militum).[1] This arrangement was scrupulously observed by Theodoric the administration continued in its old form and was staffed exclusively by Romans, and legislation remained the preserve of the Emperor[2] At the same time, the army remained the exclusive preserve of the Goths, who came under the authority of their own chiefs and courts.[3] The two peoples were further kept apart by faith the Roman population was Chalcedonian, while the Goths were Arians, although, unlike the Vandals or the early Visigoths, considerable religious tolerance was practised.[4] This complex dual system worked effectively under the capable and strong leadership of Theodoric, who knew how to carry out his own policy without alienating the Roman aristocracy, but began to break down during his later years and collapsed entirely under his heirs.