The Swedish Empire period starts in the 12th century. The early part of this period is filled with conflicts between the various Finnic tribes and the Novgodrians. Finland’s position between Sweden and Russia put it on the frontlines of either sides expansion efforts in the 12th century. Academics debate the legitimacy of several conflicts chronicled in the 12th to 14th centuries, especially the 3 so called Swedish Crusades, but the remains of numerous forts and weapons shows that the period was restless nonetheless. The Finnic people seemed the be heavily divided and their loyalties waxed and waned through the years, the Icelandic Egil’s Saga has the Norse and Northern Finnic tribes fighting against the Karelians and Novgorodians, while the Prince of Novgorod, Dmitry Alexandrovich, campaigned against the Karelians in 1278.

By early 14th century, with the various successful campaigns and crusades against the Finns, as well as colonisation of the coastal areas, and the signing of the Treaty of Nöteborg, in 1323 between Sweden and Novgorod, Finland became part of the Swedish Empire. To help secure their power and govern the land, three large stone castles were built, at Turku, Hämeenlinna and Viipuri (to use their modern Finnish names). Relations between the Swedish Empire and her Eastern neighbour were rocky at the best of times and Finland was often the frontline between the two major powers. Sometimes these conflicts consisted of the native populations, Finns, Karelians and Sami, launching raids and skirmishes deep in the territory of the other nation, at other times the organised forces of the Empires clashed with one another at the numerous strategic places in Finland.

It was during the Swedish period that many of today’s Finnish units trace their origins. For instance, the Pori Brigade traces itself to the establishment of the Pori Province Infantry Regiment. This unit was raised on the 16th February 1626 Gustavus Adolphus II for use during the 30 years war. It isn’t known how many Finns served in the Royal Swedish Army during the period but it is estimated that Finns took part in at least 38 wars of note for Sweden. Whether they be during the power struggles of the Swedish Royals or in wars between Sweden and other nations.