The outbreak of the plague caused a lull in the fighting during the year 543. The following year Khosrau defeated a Byzantine army of 30,000 men, but 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, 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.