Boris I, also known as Boris-Mihail (Michael) and Bogoris (Church Slavonic: Борисъ А҃ / Борисъ-Михаилъ Bulgarian: Борис I / Борис-Михаил; died 2 May 907), was the ruler of the First Bulgarian Empire in 852–889. At the time of his baptism in 864, Boris was named Michael after his godfather, Emperor Michael III. The historian Steven Runciman called him one of the greatest persons in history.[1]
Despite a number of military setbacks, the reign of Boris I was marked with significant events that shaped Bulgarian and European history. With the Christianization of Bulgaria in 864 paganism (i.e. Tengrism) was abolished. A skillful diplomat, Boris I successfully exploited the conflict between the Patriarchate of Constantinople and the Papacy to secure an autocephalous Bulgarian Church, thus dealing with the nobility's concerns about Byzantine interference in Bulgaria's internal affairs.
When in 885 the disciples of Saints Cyril and Methodius were banished from Great Moravia, Boris I gave them refuge and provided assistance to develop the Cyrillic script and the Slavic literature. After he abdicated in 889, his eldest son and successor tried to restore the old pagan religion but was deposed by Boris I. During the Council of Preslav which followed that event, the Byzantine clergy was replaced with Bulgarians, and the Greek language was replaced with what is now known as Old Church Slavonic.
The early 9th century marked the beginning of a fierce rivalry between the Greek East and Latin West, which would ultimately lead to the schism between the Eastern Orthodox Church in Constantinople and the Catholic Church in Rome.
As early as 781, the Empress Irene began to seek a closer relationship with the Carolingian dynasty and the Papacy. She negotiated a marriage between her son, Constantine, and Rotrude, a daughter of Charlemagne by his third wife Hildegard. Irene went as far as to send an official to instruct the Frankish princess in Greek; however, Irene herself broke off the engagement in 787, against her son's wishes. When the Second Council of Nicaea of 787 reintroduced the veneration of icons under Empress Irene, the result was not recognized by Charlemagne since no Frankish emissaries had been invited even though Charlemagne was by then ruling more than three provinces of the old Roman empire. While this improved relations with the Papacy, it did not prevent the outbreak of a war with the Franks, who took over Istria and Benevento in 788.
When Charlemagne was proclaimed Emperor of the Holy Roman Empire by Leo III, the Pope was effectively nullifying the legitimacy of Irene. He certainly desired to increase the influence of the papacy and to honour his protector Charlemagne. Irene, like many of her predecessors since Justinian I, was too weak to protect Rome and its much-reduced citizenry, and the city was not being ruled by an emperor. Thus, Charlemagne's assumption of the imperial title was not seen as a usurpation in the eyes of the Franks or Italians. It was, however, seen as such in Byzantium, but protests by Irene and her successor Nicephorus I had no great effect.
Mojmír I managed to unite some Slavic princes and established Great Moravia in 833. His successor, Rastislav, also fought against the Germans.[12] Both states tried to maintain good relations with Bulgaria on account of its considerable military power.