Christianity came to the Nordic countries during the 10th and 11th centuries. The new faith was spread by priests and monks from the archdiocese of Hamburg-Bremen as well as from England.
Christianity was brought to the Baltic region and Finland by way of Denmark and Sweden. When the Danes conquered Reval (Tallinn) in the beginning of the 13th century, the inhabitants were converted. The Swedes made three crusades in order to christianise Finland. After the third crusade, Finland became a part of Sweden.
Under the leadership of King Magnus Eriksson, the Swedes started a fourth crusade to the Russian town Novgorod. This time though, the aim was to gain control of the trade in the border districts between Finland and Russia. The crusade was a failure, and a new one was carried out in 1350. The leader this time was Israel Birgersson, the brother of Birgitta, later St. Birgitta. Israel Birgersson was killed in this battle which the Swedes lost.