He did the essential preparatory work for the German Reichnaturschutzgesetz (Nature Conservation Act) (RNG) of 26 June 1935 (RGBl.
Wolf began to maintain a database of all the world's caves and for this he had amassed numerous books and documents in his library.
After being removed from work, he was aided by Julius Riemer to continue to serve as an editor of the speleologists newsletter, "Mitteilungen über Höhlen- und Karstforschung."
[3] The Nazi research wing, the SS Ahnenerbe, became interested in caves as potential bomb shelters and on 6 July 1942, they arrested Wolf and deported him to the Theresienstadt concentration camp.
[2][4][5][6] Recent research suggests that Riemer had been asked by the Gestapo to keep in touch with Benno Wolf to prevent the latter from destroying his database of caves.