em and force their retreat. Consequently, when Khosrau invaded Roman Mesopotamia in 578, his general Maurice was able to invade Persian Arzanene and Mesopotamia, sacking a number of key towns and forcing the Persians to abandon their advance and defend their own territory. It was during this period that the ailing Emperor Justin finally died in early October 578.
The ongoing success against the Persians in the east once again allowed Tiberius to turn his gaze westward. In 579 he again extended his military activities into the remnants of the Western Roman Empire – he sent money and troops to Italy to reinforce Ravenna and to retake the port of Classis. He formed an alliance with one of the Visigothic princes in Spain who was fomenting rebellion, and his generals defeated the Berbers in North Africa.
The reality, however, was that the Empire was seriously overextended. In 579, with Tiberius occupied elsewhere, the Avars decided to take advantage of the lack of troops in the Balkans by besieging Sirmium.
At the same time, the Slavs began to migrate into Thrace, Macedonia and Greece, which Tiberius was unable to halt as the Persians refused to agree to a peace in the east, which remained the Emperor’s main priority. To top it all off, the Army of the East was beginning to become restless, as they hadn’t been paid, to the point where they threatened to mutiny.
In 580, the general Maurice launched a new offensive, raiding well beyond the Tigris. The following year (581), he again invaded Persian Armenia, and succeeded in almost reaching the Persian capital at Ctesiphon before a Persian counter-invasion of Byzantine Mesopotamia forced him to retreat back to deal with this threat.
By 582, with no apparent end to the Persian war in sight, Tiberius was forced to come to terms with the Avars, to whom he agreed to pay an indemnity and to hand over the vital city of Sirmium, which the Avars then destroyed. Unfortunately, the migration of the Slavs continued, with their incursions reaching as far south as Athens.
Although a new Persian invasion was halted with a significant defeat at Constantina in June 582, by this stage Tiberius was dying, apparently having eaten some poorly prepared, or possibly deliberately poisoned, food.
|The City of Sirmium|
Protected on two sides by the Sava River, Sirmium would have presented major
problems to any attacking army.
In the 1st century AD, Sirmium gained a status of a colony of the citizens of Rome, and became
an important military and strategic center of Pannonia province. The war expeditions of
Roman Emperors Trajan, Marcus Aurelius, and Claudius II were prepared in Sirmium.
The only known unexcavated Roman Hippodrome in the world is in Sirmium. A colossal
building about 150m wide and 450m long lies directly under the Sremska Mitrovica town
center and just beside the old Sirmium Emperor's Palace (one of just a few Sirmium publicly
accessible archeological sites). The presence of the arena has clearly affected
the layout of the present town.
Ammianus Marcellinus called Sirmium "the glorious mother of cities".
The Attacks on Sirmium (568–582 AD)
The Siege of Sirmium in 580–582 was a decisive event in the history of the Balkans.
The endless invasions by Eurasian barbarian tribes resulted in a steady "de-Latinization" of the Roman Balkan provinces.
For centuries Sirmium had served as a major civilian and military capital for the Roman Empire. The fall of the city to the Avars deprived the Romans of its major stronghold on the northwestern Danube, opening the path for devastating incursions by the Avars and their Slavic allies into the Balkans.
Sirmium, which for much of the 6th century had been controlled by the Goths and then the Gepids, had come back under Roman control in 567. The Avars appeared along the Danube at about the same time.
The Avars launched a first attack on Sirmium in 568, but were seen off by the local governor, Bonus.
Bonus resurfaces in chronicles about 568-570 as a general. His exact position in the military hierarchy is uncertain, but the location of his activities at Sirmiu