That the Western Powers would not declare war, that they would be content with some less drastic and more formal protest, this was Hitler's hope until the last minute; and all possible precautions were taken to ensure this result. It was for this reason that, on 24 August, hearing that the formal signature of the Anglo- Polish Agreement was about to take place, as it did next day, he cancelled the order, which he had already issued that same morning, to the effect that the invasion of Poland should begin on 25 August. The cancellation took the form of a postponement of D-day until 1 September. The object of the postponement was to enable him to make a last attempt, through the British Ambassador, to persuade the Western Powers to stop short of war. This last-minute effort failed, but Hitler's hope remained alive, as is shown by a further directive of 31 August. In this final directive he ordered the invasion of Poland to begin on the following morning; but he also insisted that nothing should be done which might incite Great Britain and France.

The responsibility for the opening of hostilities in the West should rest unequivocally with England and France. … The German land frontier in the West is not to be crossed at any point without my express consent. The same applies to warlike actions at sea or any which may be interpreted as such…. Defensive measures on the part of the Air Force should at first be exclusively confined to the warding-off of enemy air attacks on the frontier of the Reich.…

But the directive also assumed that the Western Powers might open hostilities; it could do nothing else, for, even after the conclusion of the Pact with Russia, Hitler could not be certain that France and Great Britain would not declare war. If they did, the task of the Armed Forces, according to the directive, would be ‘to uphold, while conserving their strength as far as possible, those conditions necessary for the successful conclusion of operations against Poland’.