What was missionary movement's greatest achievement of the Macedonian emporer?

The greatest achievement of the missionary movement under the Macedonian emperor, particularly during the reign of Emperor Basil II, was the promotion and spread of Christianity among the Slavic peoples in the Balkans. This included the establishment of the Cyrillic script by Saints Cyril and Methodius, which facilitated the translation of religious texts and the liturgy into Slavic languages. This cultural and religious advancement not only strengthened the Byzantine Empire's influence in the region but also laid the foundation for the development of Slavic national identities. Ultimately, it contributed to the long-lasting Christianization and cultural unity among the Slavic nations.