part and created the Grand Duchy of Finland out of it during the Finnish War in 1808–1809. Shortly after, in 1814, the west flank had been secured by the personal union with Norway, and after the Napoleonic Wars, the former main enemy of Sweden in the south, Denmark, was no longer any threat. The only threat left was Russia, which now stood just across the border in the north, and had possession of the Åland Islands less than 150 km from the Swedish capital Stockholm. The Swedish Navy was considered superior to the Russian in the Gulf of Bothnia, so a seaborne invasion against the coast of Norrland was not likely. And even though the Russians had invaded northern Sweden via Finland in the previous war, the general opinion was that in case of a new war, their main attack would be conducted towards Stockholm and southern Sweden. This opinion led to the thought of finding a good rear defence area where the Estates and the Swedish government could move if the capital was in danger. This in turn naturally strengthened the central defence theory. The core land () would be the place from where the main part of the field army would conduct its operations, supported by a few fortresses. The area between the two large lakes of Vänern and Vättern was the choice for this core land, with approximately the same border as Skaraborg County. Sweden above the province of Dalarna was not even considered to be included in this strategy. The realisation of the middle Sweden central defence system was finally made 5 February 1819 when King Charles XIV John decided that one main fortress, the central fortress, and two smaller "operational fortresses" were to be built. The central fortress became Karlsborg Fortress at Karlsborg, while the two operational fortresses meant to be located at either end of Vättern never were built due to lack of funds. While Norrland was not supposed to be included in this main central defence strategy, studies on how to defend this major part of the country were still conducted. However, northern Sweden was generally considered of very limited military interest and unsuitable for larger military operations due to the bad state of most of the roads, the large uninhabited areas, the large rivers and the very limited economical gain that the lands provided. The first of these studies, laid down by