It was developed by the disciples of Saints Cyril and Methodius at the Preslav Literary School (previously in Pliska as Pliska Literary School) at the end of the 9th century. After the death of Cyril, Clement of Ohrid accompanied Methodius from Rome to Pannonia and Great Moravia. After the death of Methodius in 885, Clement headed the struggle against the German clergy in Great Moravia along with Gorazd. After spending some time in jail, he was expelled from Great Moravia, and in 885 or 886 reached the borders of the Bulgarian Empire together with Naum of Preslav, Angelarius, and possibly Gorazd (according to other sources, Gorazd was already dead by that time). The four of them were afterwards sent to the Bulgarian capital of Pliska, where they were commissioned by Boris I to instruct the future clergy of the state in the Slavonic language. After the adoption of Christianity in 865, religious ceremonies in Bulgaria were conducted in Greek by clergy sent from the Byzantine Empire. Fearing growing Byzantine influence and weakening of the state, Boris viewed the adoption of the Old Slavonic language as a way to preserve the political independence and stability of Bulgaria, so he established two literary schools (academies), in Pliska and Ohrid, where theology was to be taught in the Slavonic language. While Naum of Preslav stayed in Pliska working on the foundation of the Pliska Literary School, Clement was commissioned by Boris I to organise the teaching of theology to future clergymen in Old Church Slavonic at the Ohrid Literary School. For seven years (886-893) Clement taught some 3,500 students in the Slavonic language and the Glagolitic alphabet. Commemoration Saints Cyril and Methodius' Day The canonization process was much more relaxed in the decades following Cyril's death than today. Cyril was regarded by his disciples as a saint soon after his death. His following spread among the nations he evangelized and subsequently to the wider Christian Church, and he was famous as a holy man, along with his brother Methodius. There were calls for Cyril's canonization from the crowds lining the Roman streets during his funeral procession. The brothers' first appearance in a papal document is in Grande Munus of Leo XIII in 1880. They are known as the "Apostles of the Slavs", and are still highly regarded by both Roman Catholic and Orthodox Christians. Their feast day is currently celebrated on 14 February