Ernst Casimir huwde te Weilburg op 22 februari 1634 met Anna Maria van Sayn-Wittgenstein-Sayn (.. november 1610 - Weilburg 14 april 1656 o.s.), dochter van graaf Willem III van Sayn-Wittgenstein-Sayn en Anna Odilia van Nassau-Weilburg (een dochter van graaf Albrecht van Nassau-Weilburg en Anna van Nassau-Siegen).
Engelbrecht was de derde zoon van graaf Johan I van Nassau-Siegen en Margaretha van der Mark, dochter van graaf Adolf II van der Mark en Margaretha van Kleef.   Als jongere zoon volgde Engelbrecht in eerste instantie een kerkelijke carrière.
William the Silent (24 April 1533 – 10 July 1584), also known as William the Taciturn (translated from Dutch: Willem de Zwijger), or, more commonly in the Netherlands, William of Orange (Dutch: Willem van Oranje), was the main leader of the Dutch Revolt against the Spanish Habsburgs that set off the Eighty Years' War (1568–1648) and resulted in the formal independence of the United ...
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