Adolf Hitler made many hundreds of , orders and decrees while Führer of Nazi Germany, many of them related to military policy, and the treatment of civilians in occupied countries. Many of them are direct evidence of the commission of war crimes such as the notorious Commando Order. Other orders provide evidence of crimes against humanity, such as the Hitler order establishing forced euthanasia of disabled people in 1939 under Action T4, and the Nacht und Nebel order for eliminating civilian resisters in occupied countries.
On 21 October 1938, Hitler issued a new directive to the Wehrmacht to prepare for the "following eventualities":
In 1939 Hitler issued an order which became the justification for killing disabled children and people in Action T4. It laid the basis for the Holocaust since gassing was a favoured method of murdering the many victims. The SS staff who operated the gas chambers were later employed at Auschwitz and many other concentration camps and death camps.
On 3 April 1939, the directive for Fall Weiss (Case White) was ready. It was issued on 11 April.
The first section, written by Hitler, began:
German relations with Poland continue to be based on the principles of avoiding any disturbances. Should Poland, however, change her policy towards Germany, a final settlement might become necessary in spite of the Treaty in force with Poland. The aim then will be to destroy Polish military strength, and create in the East a situation which satisfies the requirements of National Defence. The free state of Danzig will be proclaimed a part of Reich territory by the outbreak of hostilities at the latest. The political leaders consider it their task in this case to isolate Poland if possible, that is to say, to limit the war to Poland only.