Justinian I
War with the Sassanid Empire, 540–562

Belisarius had been recalled in the face of renewed hostilities by the Persians. Following a revolt against the Empire in Armenia in the late 530s and possibly motivated by the pleas of Ostrogothic ambassadors, King Khosrau I broke the "Eternal Peace" and invaded Roman territory in the spring of 540. He first sacked Beroea and then Antioch (allowing the garrison of 6,000 men to leave the city), besieged Daras, and then went on to attack the Byzantine base in the small but strategically significant satellite kingdom of Lazica near the Black Sea as requested by its discontented king Gubazes, exacting tribute from the towns he passed along his way. He forced Justinian I to pay him 5,000 pounds of gold, plus 500 pounds of gold more each year.

Belisarius arrived in the East in 541, but after some success, was again recalled to Constantinople in 542. The reasons for his withdrawal are not known, but it may have been instigated by rumours of his disloyalty reaching the court. The outbreak of the plague coupled with a rebellion in Persia brought Khosrow I's offensives to a halt. Exploiting this, Justinian ordered all the forces in the East to invade Persian Armenia, but the 30,000-strong Byzantine force was defeated by a small force at Anglon. The next year, Khosrau unsuccessfully besieged the major city of Edessa. Both parties made little headway, and in 545 a truce was agreed upon for the southern part of the Roman-Persian frontier. After that, the Lazic War in the North continued for several years: the Lazic king switched to the Byzantine side, and in 549 Justinian sent Dagisthaeus to recapture Petra, but he faced heavy resistance and the siege was relieved by Sasanian reinforcements. Justinian replaced him with Bessas, who was under a cloud after the loss of Rome in 546, but he managed to capture and dismantle Petra in 551. The war continued for several years until a second truce in 557, followed by a fifty years' peace in 562. Under its terms, the Persians agreed to abandon Lazica in exchange for an annual tribute of 400 or 500 pounds of gold (30,000 solidi) to be paid by the Romans.
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