He received a scholarship of the Lichtwark-Prize awarded by the city of Hamburg.
Kappeler accepts the nomination as professor in the Department of Painting and Graphic Arts at the University of Hanover. Apart from teaching at university he participated actively in circles where topics such as armament, nuclear energy and environment were discussed. He developed cycles like the “Nordholz project” and “Eismeerzyklos”. Kappeler then went on to studying the physiognomies of those people who became victims of justice in the waning Weimar Republic and the Nazi Regime, due to their democratic opinion towards human rights and freedom of speech. He also included those who became outcasts of the modern Federal Republic of Germany because of their critical opinions. Cycles on Theodor Lessing and Carl von Ossietzky emerged.
During his exhibitions in Bremen and Paris Kappeler met the lyricist Erich Fried. Fried’s frequent visits in the artist’s studio and the bringing together of texts and paintings led to an intensive friendship until Erich Fried’s death.
A large-sized painting referring to Theodor Lessing triggered off a nationwide discussion because of the prohibition to hang it up in the University of Hanover. Today, this work is hanging in the hall of the “Volkshochschule”, a public institution, in the capital of Lower Saxony.
Exhibitions in Berlin, Göttingen and Barcelona displayed works of his project of the “danse macabre”.