The diaries of important historical figures have always been a great source of information for scholars. Giulio Andreotti was one of these. A world-famous Italian politician involved in many Italian and international events. His diaries have recently been published in Italy. The author has read them and carried out a careful analysis of them. They shed light on many Italian and international events. In this article the author has limited himself to considering what these diaries say about the attempted coup that took place in Italy in 1970 organized by Prince Borghese. The author presents the results of his analysis and some final considerations also valid for the present time.