Johann von Leuchselring was Chancellor for the Free Imperial City of Augsburg from 1636 () through 1645 () and leading catholic negotiator in peace of Westphalia.
In Munster, Johann von Leuchselring acted as the chief magistrate in the 1645 to the Peace of Westphalia Congress as an envoy for the Catholic Council of the city of Augsburg and for the cities of Überlingen, Dinkelsbühl, Biberach, Ravensburg, Kaufbeuren, book Horn, Buchau on Federseemuseum, Rottweil, Schwäbisch-Gmündt, Offenburg, Pfullendorf, and Gengenbach, and
In the second half of 1646 war returned to Augsburg. Johann von Leuchselring was the official representative of the council of the Catholic imperial estates including committee of the Protestant citizenship, in which the patrician Johann David Herwart played a leading role ensuring a balance in negotiations between Catholics and Protestants at the Peace of Westphalia.