As the stresses on the president grew, his closest associates noticed a decline in his personality. It foreshadowed dark things to come.
“In his case, what had been hardness became cruelty, while a tendency to bluff became plain dishonesty. He often lied without hesitation and assumed that others lied to him. He believed no one any more. It had already been difficult enough dealing with him: it now became a torture that grew steadily worse from month to month. He frequently lost all self-control and his language grew increasingly violent. In his intimate circle he now found no restraining influence.”
-Heinz Guderian, Chief of the General Staff of the German Army, 1944
From “The Rise and Fall of the Third Reich,” by William Shirer.