Together with his artist friends Karel Appel, Constant, Corneille, Christian Dotremont and Joseph Noiret, Asger Jorn founded the group CoBrA in 1948; its first major exhibition took place in 1949 at the Stedelijk Museum in Amsterdam. The aim of CoBrA was to foster expressiveness and spontaneity in art and to challenge the artistic supremacy of Paris. In the early 1950s, Jorn authored manifestos, took part in the documenta, and became the leader of the 'Situationist International' movement, a group of artists who opposed capitalist functionalism. In the 1960s, he painted over oil paintings and prints of 19th century department store and salon pictures, the so-called 'Modifications' or 'Defigurations', and also made ceramics, collages, décollages and paper rips. During the last decade of his life, Jorn intensively dealt with Scandinavian photography and created numerous paintings and sculptures.