The ascent of Sweden as a major military power in Northern Europe in the seventeenth century is forever connected to the Thirty Years War. The story of King Gustavus Adolphus, and battles like Breitenfeld, Lech, Lützen, and Nördlingen mark the real beginning of the Swedish Age of Greatness. In recent decades battlefield archaeology has proved important in describing these events, widening our understanding of the military actions and their effects on local populations. This chapter focuses on Jönköping, a Swedish town where the early modern period has been examined archaeologically over three decades. This town can be used as a metaphor for Sweden during the seventeenth century as the inherent weakness of the new empire becomes evident. Events here exemplify both the visions held by the absolutist state and their consequences for ordinary people. The chapter also provides a background to the mobilization of local resources and logistics that made the Swedish war effort of 1627–48 possible.