Münster and Osnabrück were the sites of significant European negotiations from 1643 to 1648. In this spatial and temporal context, a condensed area emerged where the communicative forms of diplomacy were not only reflected but also reconfigured. The contributions in this volume focus on this dynamic. They illuminate the status and development of linguistic expressions at the Westphalian Peace Congress from the perspective of closely related historical and linguistic sub-disciplines through source-based analyses: the role of individual languages and their competition, the conditions of emergence and the exploration of sources, and the functions of their linguistic design.