Eric IX of Sweden and Bishop Henry en route to Finland. Late mediaeval depiction from Uppland

The Swedish crusades were campaigns by Sweden that took place between 1150 and 1293 against non-Christian people (the Finns proper in the 1150s, in the First Crusade; Tavastians in 1249, in the Second Crusade; and Karelians in 1293, in the Third Crusade). These three wars were actually first dubbed as ‘crusades’ by 19th-century romantic nationalist historians. The First Swedish Crusade was a (likely mythical) military expedition in the 1150s to Southwest Finland by Swedish King Eric IX and English Bishop Henry of Uppsala. The main sources of the crusade are the legend of Saint Erik and the legend of Saint Henry which describe that the reason for the crusade were the multiple raids that pagan Finns made to Sweden. The earliest written sources of the crusade are from the end of 13th Century. The crusade has traditionally been seen as the first attempt of the Catholic Church and Sweden to convert pagan Finns to Christianity, however the Christianisation of the South-western part of Finland is known to have already started in 10th century; by the 12th century, the area was probably almost entirely Christian. The Second Swedish Crusade was a possible 13th-century Swedish military expedition against the Tavastians, in present-day Finland, led by Birger Jarl. Many details of the Crusade are still debated, but unlike the doubted First Swedish crusade, there seems to be little doubt that Sweden’s effort to Christianize Finland reached a culmination in the middle of the 13th century. After the crusade, Tavastia gradually started to fall under the rule of the Catholic Church and the Swedish kingdom. There are notes of Swedish churchmen, possibly led by Finland’s bishop Thomas, being present in Tavastia ca 1230, and papal letters deplored how slowly Christianity gained ground in Finland. There was apparently a backlash against the missionaries (the Häme insurrection), and in 1237, Pope Gregory IX sent out a call for the Swedes to take up arms in a crusade against the “apostates and barbarians”. All details of the crusade are from Eric’s Chronicle, which is largely propagandist in nature, written a century after the events: the chronicle says that the crusade took place between the Battle of Sparrsätra in 1247 and the death of King Eric (XI) in 1250, and presents the Tavastians (taffwesta) as the Swedes’ opponents. According to the chronicle, the expedition was prepared in Sweden and then conducted over sea to a land on the coast, where the enemy was waiting. The Chronicle also mentioned that a castle called ‘taffwesta borg’ (interpreted as either Häme Castle (Swedish Tavastehus) or Hakoinen Castle, but there is no archaeological evidence) was established after the war. The so-called “Detmar Chronicle” of Lübeck (1340) confirmed the expedition with a short note that Birger Jarl submitted Finland under Swedish rule. Although the Chronicles attempted to paint the Crusade as a war of conquest, it was likely more of an unusually bloody phase in the ongoing process by which Finland was incorporated in the Swedish state: Sweden had a central government and a strong ideological force in the form of the Catholic church. The Finnish chieftains who joined gained power and prestige. The Third Swedish Crusade to Finland was a Swedish military expedition against the pagan Karelians in 1293 that followed the mythical First Crusade and the Second Crusade to Finland. Viborg Castle was established in 1293 on the site of a destroyed Karelian fort as the easternmost outpost of the medieval Kingdom of Sweden. After the crusade Western Karelia remained under Swedish rule until the Treaty of Nystad in 1721. According to the Eric Chronicles (Erikskrönikan) the reason behind the expedition was pagan intrusions into Christian territories: Karelians had been engaged in a destructive expedition to Sweden in 1257 which led Valdemar, King of Sweden (1250–1275) to request Pope Alexander IV to declare a crusade against them. Birger Magnusson, King of Sweden (1290 to 1318), stated in a letter that the motive of the crusade was long-time banditry and looting in the Baltic Sea region by Karelians, who had also taken Swedes and other travellers as captives and then tortured them.