This essay considers the embassy of Philip IV’s ambassador to the electoral conclave that chose Leopold I as Holy Roman Emperor in 1658. In broad terms, it considers the place of the Austrian monarchy within Spanish international priorities during the mid-seventeenth century. More specifically, it reconstructs the circumstances of the count of Peñaranda’s appointment to travel to central Europe in the summer of 1657, his relations with the ministers of the Habsburg candidate Archduke Leopold Ignatius, and the part he played in the negotiation of an electoral capitulation that was much more favourable to the Habsburgs than is often realised. Most importantly, it considers Peñaranda’s role in the peace-making process. He found himself torn between a personal desire to bring an end to the conflict between Spain and France, and his deference towards the Spanish king and his chief minister, who were not yet of a mind to come to terms with the government of Louis XIV and Cardinal Mazarin.