Byzantine mission to Great Moravia
Rastislav requests a Slavic-language mission from Byzantium
View full image ↗ How was this image made?
The creative brief sent to the image model. These are instructions, not a record of what actually happened.
Original prompt & settings (JSON) ↗The decisive act in 862 was not an alphabet appearing. It was a duke sending abroad for teachers who could preach in his people's own language.
An embassy to Constantinople
In 862 Duke Rastislav of Great Moravia sent a delegation to the Byzantine emperor Michael III, requesting clergy who could establish worship and religious instruction in a language intelligible to the Moravians.
He already had Christian missionaries. What he lacked was a church hierarchy and teaching his people could follow without Latin or Greek — and he wanted to reduce Great Moravia's dependence on the Frankish ecclesiastical hierarchy.
Michael III received the request and selected Constantine the Philosopher and his brother Methodius.
What Constantine prepared
Constantine prepared the script now called Glagolitic, along with Slavonic translations, before the missionaries reached Moravia.
In autumn 863 they arrived carrying books already translated into Slavonic and written in unfamiliar new characters, and set up instruction for local clergy.
Great Moravia was a Central European polity, not a southern Slavic one.
Not 42 Cyrillic letters
There is no sound basis for saying Constantine invented a 42-letter Cyrillic alphabet in 862. A scholarly archaeological synthesis identifies his script as Glagolitic and reports that On the Letters counted 38 characters.
The later Cyrillic script probably emerged in the Bulgarian Empire after Constantine's death, so its name does not prove his authorship.
The script's construction date is unsettled too — proposals include 855 and the short interval between the embassy and the 863 departure — and the original Glagolitic inventory is reconstructed from later evidence.
Sources
Researched 23 Aug 2026 4 sources not yet audited Date disputed
How this was checked
Researched from the web into a fact sheet and rewritten from that sheet. This article has not yet had an independent model audit. How the pipeline works →
Date disputed. Sources disagree about when this happened.
What the sources leave uncertain
- The 862 embassy is well supported, but the script’s exact construction date is not. Proposed dates include 855 and the short interval between the embassy and the 863 departure.
- The event title conflates Glagolitic with Cyrillic. The later Cyrillic script probably emerged in the Bulgarian Empire after Constantine’s death.
- The original Glagolitic inventory is reconstructed from later evidence, so a definitive 42-letter creation event cannot be maintained.