This chapter sheds light on how mercenaries of knowledge contributed on behalf of the new King of Portugal’s sovereignty on the European and Mediterranean political stage. Alongside books and manuscripts, they used their access to Portuguese products, musical instruments, and luxury foods to improve their political leverage in Rome. In the hands and letters of mercenaries of knowledge, the diverse materials of bibliopolitics worked as the mute diplomats and political sweeteners of Baroque international relations. Vicente Nogueira’s desire to return to Portugal conditioned his troubled relations during the last part of his stay in Rome and his tormented advocacy on behalf of Portuguese affairs in the city after 1640.