The conversion of the lands on the southern and eastern shores of the Baltic Sea by Germans, Danes and Swedes in the period from 1150 to 1400 represented the last great struggle between Christianity and paganism on the European continent, but for the indigenous peoples of Finland, Livonia, Prussia, Lithuania and Pomerania, it was also a period of wider cultural conflict and transformation. Along with the Christian faith came a new and foreign culture: the German and Scandinavian languages of the crusaders and the Latin of their priests, new names for places, superior military technology, and...