At the time when the alarming events described above were taking place in Great Moravia, Bulgaria was the biggest and most powerful Slav state. Moreover, because of the reasons we have already mentioned, she was in great need of an alphabet and of a Christian clergy to preach in the Slav language. The persecuted disciples of Methodius were fully aware of the needs and possibilities of the Bulgarian state, and after their teacher’s death they set out for Bulgaria, which at that time had common frontiers with Great Moravia. The local district rulers in Bulgaria gave them a hearty welcome and sent them to the capital, where Prince Boris was eagerly awaiting them. Methodius’s best known disciples who came to Bulgaria were Clement, Nahum and Angelarius. Clement was dis-patched to the south-western parts of the country as Bishop of Ohrid, while the other two remained in the capital. In only a few years, hundreds of young people, thirsty for knowledge, were taught to read and write in the Slav-Bulgarian language and were then sent as priests and administrators to all parts of the country. Scores of religious books were translated from the Greek and ousted completely the Greek language from the church services.
Grand Council of Boris
In 893 Prince Boris organized a Grand Council in the capital of Preslav, which adopted important decisions. Boris’s younger son Simeon ascended to the throne instead of Vladimir, the opponent to Christianity. The capital was transferred from heathen Pliska to Preslav. The Slav (old Bulgarian) language was proclaimed as official state and church language instead of Greek, while the numerous Greek clergy was replaced everywhere by Bulgarian priests. The sound foundations for the rapid development of an original Slav-Bulgarian culture were laid and the most important channels of Byzantine influence were cut off. The catalysts which were to speed up the process of merger between Slavs and Bulgarians, a process which had been going on for more than two centuries had been found.
The reign of Simeon, the greatest ruler of mediaeval Bulgaria, was marked with brilliant military victories which put the very existence of the Byzantine Empire to trial and turned Bulgaria into an empire. In a number of decisive battles, the biggest one at Acheloe (not far from present-day Nessebur), Simeon succeeded in crushing the military might of the Byzantines. He then led his armies in two victorious marches to the walls of Constantinople (in 921 and 923-924) which placed the Byzantine Empire on the brink of annihilation. The Bulgarian state extended from the Carpathian mountains in the north to the Aegean Sea and Central Greece in the south, from the Adriatic coast and present-day Croatia in the west to the Black Sea in the east, in other words, it occupied almost the entire Balkan Peninsula and present-day Hungary.