The main concern of Byzantium was the Muslim threat.30 The focus fell naturally on the eastern frontier, beyond which lay the Abbasid caliphate. By the mid-ninth century, however, the caliphate was no longer launching full-scale invasions, and the raids into Byzantine territory were largely headed by the amirs of Tarsus and Melitene. The reign of Michael III was marked by a series of successes against the Arabs on land: there were Byzantine victories in 855 and 859, the latter led by the emperor himself. Inscriptions atNicaea and Ankyra from this period recording their fortification by Michael are suggestive of a concerted effort.31 However, 863 is the famous date, often seen as a turning-point in the Byzantine–Arab conflict on the eastern frontier; thereafter the Byzantines were able to go on the offensive, eventually triumphing in the tenth century.32 In this year Michael’s uncle Petronas defeated the army of the amir of Melitene, who was killed in the engagement.33 During Basil’s reign, however, the Byzantines were preoccupied with crushing the Paulicians. The Paulicians were a religious group of Armenian origin deemed heretical by orthodox Byzantines, and they formed distinctive communities in the eastern borderlands.34 Following the restoration of icons under Theodora they were severely persecuted, but found sanctuary on the upper Euphrates, and Tephrike became their power centre. The Paulicians joined the Byzantines’ enemies on the eastern frontier, assisting the raids of the amir of Melitene. Their leader Karbeas died in 863, but his nephew and successor Chrysocheir appears to have been even more formidable, penetrating into Asia Minor. It was the domestic of the Schools and relative of Basil, Christopher, who managed to defeat the Paulician leader in 872, though Tephrike was only taken in 878. Basil’s efforts against Arab targets had more limited success, and his reign witnessed defeats such as the failed attack on Tarsus in 883. It seems that the reorganisation of the eastern frontier in the second half of the ninth and early tenth centuries was as important as military victories for increasing Byzantium’s strength.35 The Byzantines did not just face land war in the east; the Arabs were also a potent naval threat. The struggle for security at sea had intensified after Muslims originally from Spain had seized Crete, a vital strategic location, in the 820s (see above, p. 256). The Byzantines tried to rectify this situation. In the first year of the regency Theoktistos led an expedition to Crete, and Michael and Bardas were preparing to sail there when the caesar was murdered in 866. The reoccupation of Crete was clearly a consistent goal, but one only achieved in 961. The Byzantines are, however, credited with a successful assault on Damietta in Egypt in 853.36 A naval response was also called for in the case of Sicily, as the Arabs extended their control of the island and threatened southern Italy: their castle-by-castle advance culminated in the fall of Syracuse in 878.37 Despite this event Basil I launched a concerted effort to maintain Byzantine power in the west.38 When the Arabs threatened Ragusa in 867, the emperor responded emphatically, no doubt as concerned to stem the expansion of the Arabs as to tackle the specific problem of southern Italy and Sicily. To address the latter situation in 868 Basil entered into alliance with the Frankish emperor Louis II (855–75), who was campaigning against the Arabs in southern Italy on his own account, with the Byzantines supplying naval assistance. This arrangement was cemented with the engagement of Basil’s eldest son Constantine to Louis’ daughter. However, the alliance foundered, and Louis’ ambitions faltered and then died with him in 875.39 Despite this setback Basil maintained his aspirations. Otranto was occupied in 873, and three years later Bari was regained, as was Taranto in 880. In the closing years of Basil’s reign the general Nikephoros Phokas (grandfather of the future emperor of the same name) was active in southern Italy, and increased Byzantine control of Apulia and Calabria.40 It appears that the successes of the early Macedonians were assisted by the revival of the imperial fleet and the creation of new naval themes.41 Basil was well served by admirals such as Niketas Ooryphas and Nasar (anticipating Himerios under Leo VI), who were active throughout the Mediterranean; one success was the temporary occupation of Cyprus. Thus although Sicily slipped inexorably from Byzantine control, the empire did provide some response to the Arab naval threat. Yet this remained intractable, persisting into the reign of Leo VI (see below, pp. 499–500). A strong presence was, however, re-established in southern Italy, and was soon enhanced. Byzantine ambitions there remained live down to the twelfth century. Besides the Muslims, the Byzantines’ other major bugbear had been the Bulgars on the northern frontier, with their centre near the lower Danube at Pliska.42 As recently as 811 Nikephoros I (802–11) had been killed on campaign against them. Khan Krum subsequently ventured against Constantinople, only to die in 814 (see above, p. 257). Following his death there was an extended phase of peace between Byzantium and the Bulgars. For the mid-ninth century the key issue was religion. Under Khan Boris (c. 852–89) Christianity was spreading in the Balkans, and Boris contemplated conversion.He sought missionaries from the Franks, but Byzantium was probably uneasy at Frankish interference so close to Constantinople. The exact course of events is controversial, but whether or not Boris was threatened by a Byzantine invasion, Boris turned to Byzantium for a Christian mission.43 In the mid-860s Boris was baptised, taking the Christian name of his godfather, Michael III himself. Thus it looked as if Byzantine cultural influence in Bulgaria was assured. However, in 866 Boris turned to the papacy, seeking advice and an archbishop from Pope Nicholas I (858–67), who was then happy to score points against Constantinople.44 Papal missionaries replaced Byzantine ones. But Boris found his plans for the Bulgarian archbishopric thwarted, and in 870 cannily returned to the Byzantine fold; he procured an archbishop by skilful manoeuvring at the time of the 869–70 church council in Constantinople. Byzantine cultural influence was secured, although this also fuelled the political ambitions of Bulgaria, which were to burst forth under Boris’ even cannier son, Symeon (893–927). For the reigns of Michael III and Basil I, though, the relationship between Byzantium and Bulgaria was remarkably peaceful, and this probably freed up military energy for release elsewhere. For Byzantium the traditional concerns in the sphere of foreign affairs were the Arabs and Bulgaria, but new problems arose. The most dramatic came from the north.45 In 860 a Rus fleet suddenly appeared before Constantinople, having sailed across the Black Sea, though probably not from Kiev, which was yet to develop as a political centre. The raiders subjected the suburbs around the imperial city to plunder. Michael III was away on campaign, but he hurried back when informed of the assault. However, the fleet soon departed, perhaps simply through having amassed enough booty rather than being driven away by an act of God. While it seems that the Rus were already known to the Byzantines, the events of 860 made a deep impact. Byzantium responded to the Rus’ subsequent request for a mission, although this mission does not seem to have lasted long (see below, p. 320). The relationship remained mixed, with further Rus raids in the tenth century but also trading treaties and Rus serving with the imperial forces. Diplomatic and cultural contacts intensified, leading ultimately to the conversion of Prince Vladimir of Kiev and his people c. 988 (see below, pp. 325–6). Soon after the Rus raid, another avenue for Byzantine cultural influence opened up, when Prince Rastislav of Moravia (846–70) requested churchmen. 46 It is likely that Rastislav, sandwiched between Franks and Bulgars, turned to Byzantium in the hope of securing a political counterweight. The Byzantines embraced the opportunity, despatching in 863 the famous brothers Constantine andMethodios. They hailed from Thessaloniki, and Constantine had especially strong bonds with the court and intellectual circles of Constantinople.47 To pursue their mission in Moravia they sought to spread the word in the language of the Slavs, and to this end developed a Slavic alphabet, the first of its kind, and translated many religious texts into the literary language they coined. Their mission dissolved after the death of Rastislav and disengagement of other Slav princely patrons, who came under Frankish pressure. But their disciples had an impact in the newly Christianised Bulgaria of Boris, where they ended up as refugees after being expelled from Moravia in 885. Installed at Ohrid and Pliska, they were entrusted with the creation of a Slavic clergy and expounding Christianity in comprehensible Slavic, lessening the need for Byzantineborn clergy; but Greek remained the language of court ceremonial and, probably, the liturgy.48 Thus the outcome of the mission to Moravia had unintended consequences, not necessarily advantageous to Byzantium in so far as they nurtured the aspirations of Symeon, Boris’ son. A final development lay to the east.49 Armenia had fallen under Arab overlordship from the end of the seventh century, and the leading Armenian families (the Bagratuni and the Artsruni) had assisted in the Arab sack of Amorion in 838. But with the decentralisation of theAbbasid caliphate there came the opportunity for greater independence, and this was exploited by Ashot I Bagratuni (‘the Great’), prince of princes, who in 884 was crowned king of Armenia. Under Michael III and Basil I political relations with Armenia were fostered, Basil recognising Ashot as prince of princes (arch¯on t¯on archont¯on).50 These friendly relations persisted into the tenth century, and assisted in Byzantium’s expansion eastwards.