History for ready reference, Volume 1, A-Elba
chapter 4.
CHRISTIANITY: 9th-10th Centuries. The Eastern Church as a missionary Church.
"If the missionary spirit is the best evidence of vitality in a church, it certainly was not wanting in the Eastern Church during the ninth and tenth centuries of our era. This period witnessed the conversion to Christianity of the principal Slavonic peoples, whereby they are both linked with Constantinople, and bound together by those associations of creed, as well as race, which form so important a factor in the European politics of the present day. The Moravians, the Bulgarians, and the Russians were now brought within the fold of the Church; and the way was prepared for that vast extension of the Greek communion by which it has spread, not only throughout the Balkan peninsula and the lands to the north of it, but wherever Russian influence is found--as far as the White Sea on the one side, and Kamtchatka on the other, and into the heart of Central Asia. The leaders in this great work were the two brothers, Cyril and Methodius, who in consequence of this, have since been known as the Apostles of the Slavonians. What Mezrop did for the Armenians, what Ulfilas did for the Goths, was accomplished for that race by Cyril in the invention of a Slavonic alphabet, which from this cause is still known by the name of the Cyrillic. The same teacher, by his translation of the Scriptures into their tongue, provided them with a literary language, thereby producing the same result which Luther's Bible subsequently effected for Germany, and Dante's Divina Commedia for Italy. It is no matter for surprise that, throughout the whole of this great branch of the human race--even amongst the Russians, who owed their Christianity to another source--the names of these two brothers should occupy the foremost place in the calendar of Saints. It is not less significant that their names are not even mentioned by the Byzantine historians."
_H. F. Tozer, The Church and the Eastern Empire, chapter 7._
CHRISTIANITY: 9th-11th Centuries. The Western Church as a missionary Church.
The earlier missions of the Western Church have been described, but it is noteworthy that again and again missions to the same regions are necessary. It requires such a map as the one accompanying this article to make plain the slowness of its diffusions and the long period needed to produce even a nominally Christian Europe. "The views of Charlemagne for the conquest and conversion of the Northern heathens [see SAXONS: A. D. 772-804], were not confined to the limits, wide as they were, of Saxony. The final pacification effected at Salz, seemed to open his eyes to more extensive enterprises in prospect. Political may have combined with religious motives in inducing him to secure the peace of his new frontiers, by enlisting the tribes of Denmark under the banner of the Cross, and he conceived the idea of planting a church in the neighbourhood of Hamburg, which should become a missionary centre. This plan, though interrupted by his death, was not neglected by his son Louis le Debonnaire, or 'the Pious.' ... But it is easier to propose such a plan than find one willing to carry it out. The well-known ferocity of the Northmen long deterred anyone from offering himself for such a duty. At length he received intelligence from Wala, the abbot of Corbey, near Amiens, that one of his monks was not unwilling to undertake the perilous enterprise, The intrepid volunteer was Anskar."
_G. F. Maclear, Conversion of the West: The Northmen,