The SOPD was founded in 1951 by Jan Hartman, formerly of the [[National Socialist Movement in the Netherlands|NSB]],<ref name="Roos2010">{{cite book|last1=Roos|first1=Jan de|last2=Roos-Van Rooden|first2=Thea|title=Moed en overmoed: een biografie van burgemeester Dirk Frans Pont|url=http://books.google.com/books?id=NIzv8VukcxkC&pg=PA193|accessdate=1 May 2012|year=2010|publisher=Uitgeverij Verloren|isbn=9789087041847|pages=193 n.14}}</ref> the fascist party that allied itself with the German Nazi movement after the [[History of the Netherlands (1939–1945)|occupation of the Netherlands]] in 1939. Hartman became the organization's secretary. A co-founder was the lawyer [[Jan Wolthuis]], another former NSB member who had been a "peace judge" during the German occupation,<ref name="Roos2010"/> essentially a political office meant to render [[Anton Mussert]] immune from prosecution.
The organization was "tolerated" by the Dutch government, but thea political party, formedfounded by theSOPD organizationmember [[Paul van Tienen]],<ref name="Mudde2003">{{cite book|last=Mudde|first=Cas|title=The Ideology of the Extreme Right|url=http://books.google.com/books?id=spT-NgRm3f8C&pg=PA117|accessdate=1 May 2012|date=2003-02-22|publisher=Manchester UP|isbn=9780719064463|pages=117–18}}</ref> the [[National European Social Movement|Nationaal Europese Sociale Beweging]] ("National European Social Movement"), was banned by the [[Supreme Court of the Netherlands]] in 1954<ref name="Schans2011"/>/1955.<ref name="Art2011">{{cite book|last=Art|first=David|title=Inside the Radical Right: The Development of Anti-Immigrant Parties in Western Europe|url=http://books.google.com/books?id=9dUTXJakqLoC&pg=PA78|accessdate=1 May 2012|date=2011-02-21|publisher=Cambridge UP|isbn=9780521720328|page=78}}</ref> The party had numbered between 100 and 400 members, all "old comrades", and was banned on the basis of a 1944 decree signed by [[Wilhelmina of the Netherlands|Queen Wilhelmina]], the "Resolution concerning the Dissolution of Treasonable Organisations".<ref name="Mudde2003"/>
