Ottavio Piccolomini (1599-1656) was a Tuscan nobleman living the most of his life out the native country in the service of the Habsburg empire across Europe, whose activity has been studied within the framework of the Thirty Years' War. His participation in the several stages of the conflict, from his youth as a pike-bearer till his maturity as an imperial envoy, has marked most of the contributions on his life and career. This research focuses, instead, on his cultural interests, to understand the process of his self fashioning as soldier, courtier and patron at the imperial court. By analysing written and visual sources, this works investigates how cultural patronage was instrumental in the construction of Piccolomini's social and political persona and how this was affected by the mobility inherent in his military career. The transnational dimension of his military activity, between Italy, the Habsburg empire, Spain and the Spanish Netherlands inevitably determined the quality, the opportunity and the modality of his purchases of art and luxury goods, and shaped his action as a patron. The analysis of Piccolomini's correspondence sheds light on the importance of agency in the process of acquisition and commission of artworks and shows the pivotal role of an extended, flexible and reliable network of agents (family, comrades, subordinates, other patrons) for the representative needs of someone so often absent from the court on duty. By comparing different episodes in Piccolomini's patronage this research tries to show how investments in art could be used for the building and the maintenance of a social and political reputation and how this was specifically essential for foreign imperial servants in Vienna. By considering the investments in art of a military man, this work presents patronage – usually studied in relation to collectors, art lovers and connoisseurs – as one of the most common expressions for the identity of European nobilities in the early modern time.