The author has been researching the role of jiu jitsu and of its practitioners in the Dutch resistance during the Second World War. This publication is a first result of that research, in which the entire jiu jitsu photo album of Hans van der Stok is included. Another volume on several other Dutch practitioners of jiu jitsu who also were involved in resistance activities in Holland during the War will be published in the near future.

Johan Smits (b. 1961) studied at the Academy for Library and Documentation Studies in The Hague. He works for the Dutch Ministry of Foreign Affairs and is a practitioner and teacher of jiu jitsu in the Netherlands.