Early in the morning of 10 May 1940 the might of the German armed forces rolled into The Netherlands bringing to an end more than a century of jealously guarded and carefully maintained neutrality. To explain the nature of this central tenet of Dutch foreign policy, it is necessary to look at its origins and development in the inter-war period, before examining the ways in which Dutch and other historians have interpreted it and passed judgement.

Neutrality, as practised in the 1930s, owed its form primarily to the experiences of The Netherlands as a neutral state during and immediately after the First World War. In 1914, the Dutch had proclaimed their neutrality in line with the second Hague Peace Conference (1907). Unable to defend all their frontiers, they trod a fine line between the belligerent states on military, political, and economic matters, protesting violations where they thought it possible or necessary to impress others and reaching tacit agreements where positions could not be maintained. Apart from the military issues raised by the belligerents in relation to Dutch territory, the most vexed questions on The Netherlands' neutrality related to her economic role. Germany was anxious to exploit all the possibilities which the neutrality of its neighbour provided to break the British blockade, while Britain, France, and later America sought to limit these same opportunities.