In the programme "The Making of "The World at War"", included in the DVD set, Jeremy Isaacs explains that priority was given to interviews with surviving aides and assistants rather than recognised figures. The most difficult person to locate and persuade to be interviewed was Heinrich Himmler's adjutant Karl Wolff. During the interview he admitted to witnessing a large-scale execution in Himmler's presence. Isaacs later expressed satisfaction with the content of the series, noting that if it had been unclassified knowledge at the time of production, he would have added references to British codebreaking efforts.