German People's Union
Dahl was married to Regina Dahl, a journalist with the "National Zeitung", a weekly extreme right newspaper published by Gerhard Frey. Dahl was a spokesman for the German People's Union, a nationalist political party founded by Frey. In 2004, Frey and Hajo Herrmann published an abstract of Dahl's biography in the book "Helden der Wehrmacht – Unsterbliche deutsche Soldaten [Heroes of the Wehrmacht – Immortal German soldiers]". This publication was classified as a far-right wing publication by Claudia Fröhlich and Horst-Alfred Heinrich. Dahl died on 25 November 1985 of heart failure in Heidelberg.