though it is postulated that it was a result of treachery. Petar would later defeat Pribislav, Mutimir's son, and take the Serbian throne. Motivations for baptism and conversion to Christianity There are a number of versions as to why Boris converted to Christianity. Some historians attribute it to the intervention of his sister who had already converted while being at Constantinople. Another story mentions a Greek slave in the ruler's court. A more mythological version is the one in which Boris is astonished and frightened by an icon of Judgement day and thus decides to adopt Christianity. Richard B. Spence sees the decision as deliberate, practical, and politic. For a variety of diplomatic reasons, Boris became interested in converting to Christianity. In order to both extend his control over the Slavic world and gain an ally against one of the most powerful foes of the Bulgars, the Byzantine Empire, Boris sought to establish an alliance with Louis the German against Ratislav of Moravia. Through this alliance, Louis promised to supply Boris with missionaries, which would have effectively brought the Bulgars under the Roman Church. However, late in 863, the Byzantine Empire under Emperor Michael III declared war on Boris and the Bulgars during a period of famine and natural disasters. Taken by surprise, Boris was forced to make peace with the Byzantines, promising to convert to Christianity according to the eastern rites, in exchange for peace and territorial concessions in Thrace (he regained the region of Zagora recently recovered by the Byzantines). At the beginning of 864, Boris was secretly baptized at Pliska by an embassy of Byzantine clergymen, together with his family and select members of the Bulgarian nobility. With Emperor Michael III as his godfather, Boris also adopted the Christian name Michael. Separate from diplomatic concerns, Boris was interested in converting himself and the Bulgarians to Christianity to resolve the disunity within the Bulgarian society. When he ascended to the throne, the Bulgars and Slavs were separate elements within Boris' kingdom, the minority Bulgars constituting a military aristocracy. Richard Spence compares it to the relationship between the Normans and Saxons in England. Religious plurality further contributed to divisions within the society. The Slavs had their own polytheistic belief system while the Bulgar elite believed in Tangra, the Sky God, or God of Heaven. The arrival of Methodius and his followers introduced the Cyrillic alphabet, freeing the Bulgarians from