The conversion of the peoples living on the eastern shores of the Baltic Sea was a major component of the crusades to these regions, which took place from the end of the twelfth century to the end of the fourteenth. The actual acceptance of Christianity, however, was a long process extending into the early modern period.
The attempt to integrate the territories of present-day Estonia and Latvia into the system of bishoprics of the Roman Church was first undertaken by Eskil, archbishop of Lund, who appointed a monk named Fulco as bishop of Estonia in the 1170s, although there is no evidence that he ever visited the country. The ambitions of the bishopric of Hamburg-Bremen meant that Danish and German parties became rivals in the Christianization of the Baltic lands.
In the mid-1180s a canon of the cathedral of Bremen called Meinhard (d. 1196) arrived with German merchants at the mouth of the Düna River, and the first systematic attempts at conversion began, initially among the Livs and Lettgallians. The achievements of Meinhard, appointed bishop of Üxküll (mod. Ikšķile, Latvia) in 1186, and his successor, Berthold of Loccum, remained modest. Large-scale Christianization began only with the military campaigns organized at the beginning of the thirteenth century by Albert of Buxhovden, bishop of Riga, in the Livic, Lettgallian, and south Estonian territories and King Valdemar II of Denmark in the northern and western Estonian territories. The Livs were baptized by 1206, and from 1208 onward systematic military campaigns were launched against the Estonians by the crusaders based in Riga and the Order of the Sword Brethren (founded in 1202). In 1211 a Cistercian monk called Dietrich, a companion of the late bishop Meinard, was appointed bishop of Estonia, and after the defeat of the Estonians in 1219 by Valde- mar II, Vescelin was appointed Danish bishop of Reval (mod. Tallinn, Estonia). The Estonians were formally baptized in 1215-1227. In 1220 Bishop Albert appointed his brother Hermann as bishop of Dorpat (mod. Tartu, Estonia). The first bishop of Osel-Wiek, Gottfried, is mentioned in 1228, and the bishopric of Curonia in northern Latvia was established at the end of the 1230s.
The first attempts to convert Prussia were not successful. Long before the period of the crusades, the missionaries Adalbert of Prague (d. 997) and Bruno of Magdeburg (d. 1009) had been killed by Prussian and Lithuanian tribes. The conquest of Prussia was initiated by Conrad, duke of Mazovia, with the help of the Teutonic Order. In 1243, four bishoprics (for Pomesania, Warmia, Sambia, and Kulm) were created to replace the single bishopric of Prussia. The largely forceful Christianization of Prussia was characterized by serious setbacks and heathen revolts and was not accomplished until 1283. In 1245 Albert Suerbeer was consecrated as the first archbishop of Prussia, Livonia, and Estonia, and in 1253 he made Riga his seat. The bishop of Tallinn remained a suffragan of the archbishop of Lund up to the Reformation.
Lithuania retained paganism until the end of the fourteenth century. In the mid-thirteenth century Grand Duke Mindaugas made an attempt to accept Christianity, largely for political reasons, but lost the support of his heathen subjects, apostatized, and was murdered in 1263. Lithuania was officially converted in 1386 when Grand Duke Jogaila accepted baptism in order to become king of Poland. Samogitia was conquered by the Teutonic Order in 1405 and accepted Christianity by 1414.
There are very few sources representing the inner religious attitudes of the population during the process of conversion. At first, Christianization was hampered by the small numbers of missionaries, by their inadequate knowledge of local languages, and not least by the resistance of the native peoples. The launching of crusades to Livonia and Prussia increased the rate of conversion, but it is evident that baptism was often imposed by force or by the threat of violence, and it is difficult to establish how far the converts actually accepted Christian beliefs. Certainly revolts of the Prussians and Estonians against their new rulers were often accompanied by apostasy and reversion to pagan religious practices. In 1199 Pope Innocent III described the local peoples as venerating forces of nature and impure ghosts, and similar remarks occur in synodal statutes from Riga (1428, 1437) and Osel-Wiek (1505, 1517). Innocent ordered clerics to be moderate in imposing penance on the newly converted, and during the following centuries similar admonitions stressed the importance of teaching the native inhabitants the basic catechetical texts in their own languages and forcing them to give up pagan habits such as using their old burial places, saying auguries, and venerating heathen gods.
The process of conversion in the countryside of Livonia and Prussia seems to have been relatively slow and for a long period burdened with pagan or half-pagan habits. In Livonia so-called non-German chancels existed at least from the fifteenth century in many urban churches, monasteries, and friaries and were able to minister to the native population living in the towns.
The first written texts in local languages (the Pater Nos- ter, the Ave Maria, and the creed) date from the first part of the sixteenth century. The existence of earlier texts of this kind is probable but cannot be proved because of the poor survival of any medieval religious texts in this region, whether Latin or vernacular.