 He applied for the post of Thomaskantor when Tobias Michael died on 26 June 1657, and he was appointed on 17 July; the four other candidates to whom he was preferred included Adam Krieger.In Knüpfer the Thomaskirche found a "Kantor" and the city of Leipzig a director of music who came close to the musical and intellectual calibre of Sethus Calvisius and Johann Hermann Schein, his two predecessors.During his 19-year tenure Leipzig once again became the leading musical city in central Germany following the sharp decline resulting from the Thirty Years War, the long Swedish occupation of the city and his protracted illness.