The aim of this article is thus to add to this subject by investigating these events from a military point of view. The study of medieval warfare in Sweden has hitherto yielded little interest among scholars. In the battle that followed the king was defeated and fled back to Stockholm. In April his army was ambushed in Hälla forest in Västmanland by forces commanded by the bishop. In order to crush the uprising the king quickly responded with a war campaign against the insurgents. more In the winter of 1464, the Swedish bishop Kettil Karlsson (Vasa) instigated an uprising against King Christian I of Oldenburg who at the time ruled all of Scandinavia. In the winter of 1464, the Swedish bishop Kettil Karlsson (Vasa) instigated an uprising against K. The primary aim of this study is not to study mercenaries as military assets from a traditional state perspective, but to study the military enterprisers themselves as commercial agents on the Baltic market. Though, the question of why and how the Swedish state contracted foreign mercenaries during the sixteenth century have seldom been studied – neither the business strategies of the enterprisers themselves. Previous research has ascertained the presence of mercenaries in Swedish service during the early Vasas. The century in between is a fairly pristine area for further research on this matter. In my thesis I also show how contracts with German companies of mercenaries became an established practise for military recruitment in Sweden already during the 1490s. During the Thirty Years war, the Swedish strategies for contracting mercenaries are a well-known phenomenon. The aim is to present and discuss productive research problems on the subject of mercenaries. more In this essay I outline my forthcoming research project on military enterprisers in sixteenth century Sweden and the Baltic Sea area. In this essay I outline my forthcoming research project on military enterprisers in sixteenth cen.