Byzantium and Bulgaria, at the same time renewing the Serbian-Byzantine alliance with Časlav of Serbia, returning independence the same year. In September 927 Peter arrived before Constantinople and married Maria (renamed Eirene, "Peace"), the daughter of Romanos' eldest son and co-emperor Christopher, and thus his granddaughter. On this occasion Christopher received precedence in rank over his brother-in-law Constantine VII, something which compounded the latter's resentment towards the Lekapenoi, the Bulgarians, and imperial marriages to outsiders (as documented in his composition De Administrando Imperio). From this point on, Romanos' government was free from direct military confrontation with Bulgaria. Although Byzantium would tacitly support a Serbian revolt against Bulgaria in 931, and the Bulgarians would allow Magyar raids across their territory into Byzantine possessions, Byzantium and Bulgaria remained at peace for 40 years, until Sviatoslav's invasion of Bulgaria. Campaigns in the East Romanos appointed the brilliant general John Kourkouas commander of the field armies (domestikos ton scholon) in the East. John Kourkouas subdued a rebellion in the theme of Chaldia and intervened in Armenia in 924. From 926 Kourkouas campaigned across the eastern frontier against the Abbasids and their vassals, and won an important victory at Melitene in 934. The capture of this city is often considered the first major Byzantine territorial recovery from the Muslims. In 941, while most of the army under Kourkouas was absent in the East, a fleet of 15 old ships under the protovestiarios Theophanes had to defend Constantinople from a Kievan raid. The invaders were defeated at sea, through the use of Greek fire, and again at land, when they landed in Bithynia, by the returning army under Kourkouas. In 944 Romanos concluded a treaty with Prince Igor of Kiev. This crisis having passed, Kourkouas was free to return to the eastern frontier. In 943 Kourkouas invaded northern Mesopotamia and besieged the important city of Edessa in 944. As the price for his withdrawal, Kourkouas obtained one of Byzantium's most prized relics, the mandylion, the holy towel allegedly sent by Jesus Christ to King Abgar V of Edessa. John Kourkouas, although considered by some of his contemporaries "a second Trajan or Belisarius," was dismissed after the fall of the Lekapenoi in 945. Nevertheless, his campaigns in the East paved the way for the even more dramatic reconquests in the middle and the second half of the 10th century. Internal policies Romanos I Lekapenos attempted to strengthen