Süha Konuk
The peace treaty concluded in 562 between Emperor Justinian I and the Sasanian ruler Khosrow I was broken in 572 by Justin II (565–578). The war, launched with considerable expectations, turned into a grave disaster for Byzantium with the loss of the strategic frontier city of Dara in 573. Following these developments, Justin II's mental health deteriorated completely, rendering him entirely incapable of governing. The Caesar Tiberius effectively assumed power in the shadow of Empress Sophia and ruled the empire with the title of Caesar until Justin's death in 578. The failure of Byzantium's siege of Nisibis in spring 573, and moreover the loss of Dara, compelled Byzantium to seek an urgent truce with the Sasanians. During this period, Tiberius aimed to maintain peace at any cost until a new army could be established. However, the appointment of Maurice as magister militum per Orientem in 578 marked a decisive turning point in this defensive doctrine, enabling Byzantium to regain the initiative on the eastern front. This article focuses on how Tiberius II managed the Sasanian war during the four years he governed the empire with the title of Caesar.