Byzantine military-administrative units in the Eastern Bulgaria and on the Lower Danube during the reign of John I Tzimisces

In the spring-summer of 971, after the victories over the Grand Prince of Kiev Svyatoslav I who seized Bulgaria, the Byzantine Emperor John I Tzimisces conquered the territories of Eastern Bulgaria and the Lower Danube. The main cities of the region, Preslav and Dristra, under Byzantine rule have been renamed Ioannoupolis şi Theodoroupolis. The Bulgarian political formation maintained in Macedonia during the reign of Cometopuli brothers led the policy of restoration of the Bulgarian Tsardom. In the conquered territories John I Tzimisces has organized new Byzantine themes: the Strategy of Ioannoupolis in Eastern Bulgaria (spring 971) and the Catepanate of The- odoroupolis on the Lower Danube (summer 971). But soon the Catepanate of Theodoroupolis was replaced with the Strategy of Dristra or Dorostolon (971 or 972). Due to the intensification of the Bulgarian threat the Strategy of Dristra (Dorostolon) was replaced with the Catepanate of Western Mesopotamia (before 975).