The mission to the Slavs, beginning under the dual blessing of Byzantium and Rome, promised quick success, but the story of Constantine records the beginning of opposition as well, against which the brothers were obliged to defend their work. He was not destined to return to Moravia but died in Rome in 869, becoming a monk just before his death and obtaining his brother’s promise to continue the work he had begun.

Methodius was also unable to return to the scene of his first labors. While the brothers were in Rome, German pressure on Moravia had increased, and after 870 it became part of the Western empire. Methodius stayed farther south with the Pannonian Prince Kotzel, who shared Rostislav’s views on strengthening Christianity among the Slavs as a defense against Germanism.

Here, in all probability, he introduced the Slavic liturgy for the first time, and this caused many of his troubles. In 794 one of the Western councils had forbidden the celebration of the liturgy in any language but Latin, Greek, or Hebrew; technically, Methodius had broken this law. Besides, although Latinism was weak in Moravia, Pannonia had been under the administration of the Latin archbishopric of Salzburg for seventy-five years, and conflict was inevitable. The missionary to the Slavs was obviously “out of bounds.”

Alexander Schmemann, A History of the Orthodox Church

Alexander Schmemann, A History of the Orthodox Church

Both Kotzel and the archbishop of Salzburg appealed to Rome, which again supported Methodius. He was made head of a separate diocese of Pannonia, subordinate to Rome. But his enemies were not pacified.

Methodius was accused of flouting the Church canons, condemned by the Sejm in Regensburg (an assembly of secular and ecclesiastical notables), and forced to languish in prison for two and a half years.

All his complaints to Rome were intercepted. Under Pope John VIII he again received firm support for a while. Understanding the full significance of the Slavs, the pope appointed him archbishop of Moravia and stood by him, despite never-ending intrigues. So in ceaseless struggle, defending his own rights, betrayed by his enemies but supported by the people, Methodius lived on until 885.

During this time immense work was accomplished, which was to fertilize the whole Slavic world. But the immediate work of the brothers fell to pieces among the western Slavs after Methodius’ death. They could not hold off German pressures, and Pope Stephen, who could not understand the policy of his predecessors, simply liquidated the whole Slavic mission.

The disciples of Methodius were driven out of Moravia, and only in the nineteenth century, during a time of Slavic renewal, did the work of Cyril and Methodius again become a rallying point for national liberation and western Slavic culture.

Alexander Schmemann, A History of the Orthodox Church