Less than a decade after the Fifty-Year Peace Treaty of 562, tensions mounted at all points of intersection between the two empires' spheres of influence, as had happened before when war broke out in the 520s.

After a victory at Sargathon in 573, they laid siege to Nisibis and were apparently on the point of capturing this, the chief bulwark of the Persian frontier defences, when the abrupt dismissal of their general Marcian led to a disorderly retreat.

[5] Taking advantage of Byzantine confusion, Sassanid forces under Khosrow I (r. 531–579) swiftly counter-attacked and encircled Dara, capturing the city after a four-month siege.

[10] In 576, Khosrow I set out on what was to be his last campaign and one of his most ambitious, staging a long-range strike through the Caucasus into Anatolia, where Persian armies had not been since the time of Shapur I (r. 240–270).

Khosrow now sued for peace, but a victory in Armenia by his general Tamkhosrow over his recent nemesis Justinian stiffened his resolve and the war continued.

However, around this time the future Khosrow II was put in charge of the situation in Armenia, where he succeeded in convincing most of the rebel leaders to return to Sassanid allegiance, although Iberia remained loyal to the Byzantines.

The advantage gained at Constantina was lost later in the year when his successor as magister militum of the East, John Mystacon, was defeated on the river Nymphios by Kardarigan.

[17] During the mid-580s, the war continued inconclusively through raids and counter-raids, punctuated by abortive peace talks; the one significant clash was a Byzantine victory at the Battle of Solachon in 586.

[18] The arrest by the Byzantines of al-Mundhir's successor al-Nu'man in 584 led to the fragmentation of the Ghassanid kingdom, which reverted to a loose tribal coalition and never regained its former power.

Meanwhile, in the Caucasus, Byzantine and Iberian offensives were repulsed by the Persian general Bahram Chobin, who had recently been transferred from the Central Asian front where he had brought a war with the Göktürks to a successful conclusion.

Khosrow not only returned Dara and Martyropolis in exchange for Maurice's assistance, but also agreed to a new partition of the Caucasus by which the Sassanids handed over to the Byzantines many cities, including Tigranokert, Manzikert, Baguana, Valarsakert, Bagaran, Vardkesavan, Yerevan, Ani, Kars, and Zarisat.

However, this situation was soon dramatically overturned, as the alliance between Maurice and Khosrow helped trigger a new war only eleven years later, with catastrophic results for both empires.