(1926-2006) Joachim C. Fest was a German historian and journalist, who wrote a major German-language biography of Adolf Hitler and was co-publisher of the Frankfurter Allgemeine Zeitung. He was politically conservative and worried about the effect of the left on modern Germany.  Hans Mommsen, a historian of the moderate left, complained of bias in Fest's work.
Not only was the 1973 biography important in being written by a German, it also challenged the conventional wisdom that primarily economic factors led to the rise of the Nazi Party. Fest
t explained Hitler’s success in terms of what he termed the “great fear” that overcame the German middle classes as a result of Bolshevism and First World War dislocation, but also more broadly in response to rapid modernisation, which led to a romantic longing for a lost past. This led to resentment of other groups — especially Jews — seen as agents of modernity. It also made many Germans susceptible to a figure such as Hitler who could articulate their mood. “He was never only their leader, he was always their voice . . . the people, as if electrified, recognised themselves in him."
Among his other works was a biography of Albert Speer. While Ernst Roehm had been Hitler's only friend that spoke with him in the intimate German form, Fest is among those that thought a form of love existed between Speer and Hitler.
Various critics have detected 'traces of an erotic motif' in the relationship between Hitler and Speer, with architecture providing the common ground for discussion and agreement. Indeed, the strange friendship very soon transcended professional amity. It developed into an attachment of a kind unfamiliar to both men and beset with many inhibitions ... It endured right up to the very last hours, when Speer returned to Berlin engulfed by flames to say good-bye to the man who, he believed, had put the world at his feet and then destroyed it.
- Joachim C. Fest (1973), Hitler, Harcourt Brace Jovanovich, p. 487
- "Joachim Fest", Sunday Times, 13 September 2006
- Joachim Fest, Speer: The Final Verdict, Harcourt Brace Jovanovich