The plan to seize Belgium and the Netherlands was considered in August 1938, when the attack on Czechoslovakia was being formulated, and the possibility of war with France and England was contemplated. The advantage to Germany of being able to use these countries for their own purposes, particularly as air bases in the war against England and France, was emphasised. In May of 1939. when Hitler made his irrevocable decision to attack Poland, and foresaw the possibility at least of a war with England and France in -consequence, he told his military commanders:
" Dutch and Belgian air bases must be occupied.... Declarations of neutrality must be ignored."
On August 22nd in the same year, he told his military commanders that England and France, in his opinion, would not " violate the neutrality of these countries." At the same time he assured Belgium and Holland and Luxemburg that he would respect their neutrality; and on the 6th October, 1939, after the Polish campaign, he repeated this assurance. On the 7th October General von Brauchitsch directed Army Group B to prepare " for the immediate invasion of Dutch and Belgian territory, if the political situation so demands." In a series of orders, which were signed by the defendants Keitel and Jodl, the attack was fixed for the 10th November, 1939, but it was postponed from time to time until May of 1940 on account of weather conditions and transport problems.
At the conference on the 23rd November, 1939, Hitler said:
" We have an Achilles heel: The Ruhr. The progress of the war depends on the possession of the Ruhr. If England and France push through Belgium and Holland into the Ruhr, we shall be in the greatest danger.... Certainly England and France will assume the offensive against Germany when they are armed. England and France have means of pressure to bring Belgium and Holland to request English and French help. In Belgium and Holland the sympathies are all for France and England.... If the French Army marches into Belgium in order to attack us, it will be too late for us. We must anticipate them.... We shall sow the English coast with mines which cannot be cleared. This mine warfare with the Luftwaffe demands a different starting point. England cannot live without its imports. We can feed ourselves. The permanent sowing of mines on the English coasts will bring England to her knees. However, this can only occur if we have occupied Belgium and Holland . . . My decision is unchangeable; I shall attack France and England at the most favourable and quickest moment. Breach of the neutrality of Belgium and Holland is meaningless. No one will question that when we have won. We shall not bring about the breach of neutrality as idiotically as it was in 1914. If we do not break the neutrality, then England and France will. Without attack, the war is not to be ended victoriously."
On the 10th May, 1940, the German forces invaded the Netherlands, Belgium and Luxemburg. On the same day the German Ambassadors handed to the Netherlands and Belgian Governments a memorandum alleging that the British and French armies, with the consent of Belgium and Holland, were planning to march through those countries to attack the Ruhr, and justifying the invasion on these grounds. Germany, however, assured the Netherlands and Belgium that their integrity and their possessions would be respected. A similar memorandum was delivered to Luxemburg on the same date.
There is no evidence before the Tribunal to justify the contention that the Netherlands, Belgium and Luxemburg were invaded by Germany because their occupation had been planned by England and France. British and French staffs had been cooperating in making certain plans for military operations in the Low Countries, but the purpose of this planning was to defend these countries in the event of a German attack.
The invasion of Belgium, Holland and Luxemburg was entirely without justification.
It was carried out in pursuance of policies long considered and prepared, and was plainly an act of aggressive war. The resolve to invade was made without any other consideration than the advancement of the aggressive policies of Germany.
Sources: The Avalon Project