Dear Prince_Lieven,we never had a Willem IX,the Nassau's,as we know them started off with Count Heinrich"The Rich"of Nassau(1180-1250),he was married to Dutch Machteld of Guelders.Their eldest son Walram is the ancestor of the Nassau-Weilburg line and thus of the present GrandDuke of Luxembourg,while their youngest son Otto is the ancestor of the Ottonian line and thus Queen Beatrix.
The Nassau-Dillenburg line gained importance in the Netherlands as Count Engelbrecht(1370-1442) married dutch heiress Johanna of Polanen(ao,Breda).
Count Hendrik III of Nassau,Lord of Breda,Stadtholder of Holland and Zealand(1483-1531)married,2nd,Claudia of Chalon-Orange,(she was the daughter of Jean II,Prince of Orange).They had one son,René of Chalon,(1519-1544)Count of Nassau,Prince of Orange(1538)he married Anne of Lorraine.From this marriage was a daughter,born and died also in 1544.Upon René's death,the title Prince of Orange was inherited by Count Willem of Nassau,his nephew,known as Willem I,Prince of Orange,Count of Nassau,Viscount of Antwerp,Baron of Breda,Stadtholder of Holland,Zeeland and Utrecht (1559) aka William the Silent.Son of Willem "the rich",Count of Nassau Dietz and Vianden and Juliana van Stolberg.
Upon inheriting the title Prince of Orange,Emperor Charles V demanded for Willem to be educated at his Court in Brussels,he became a confidant of the Emperor.
He married first Anna van Egmond,Countess of Buren in 1551,three children,
1)Maria 1553-1554,
2)Filips Willem,Prince of Orange 1554-1618,married Eleonore of Bourbon-Condé,no issue
3)Maria 1556-1616
Filips was "kidnapped" to Madrid by order of Philips II,King of Spain at the start of the 80 year war of Independence from Spanish rule(1568-1648),and he remained catholic due to this,while Willem The Silent converted to protestantism.Filips never played any role in The Netherlands,he remained a prisoner all his life.
All in all Willem I The Silent had 15 issue by his subsequent wives,as well as a few out of wedlock,between Anna van Buren and Anna of Saksen.
By Anna of Saksen(marriage was annulled):Prins Maurits,he never married,but had issue by his mistresses
Frederik Hendrik and Amalia von Solms Braunfels had issue,9,and became the ancestors of virtually every present day Royal House in Europe.
The Mary's,with all respect,are already mentioned,so I move on to Willem IV.
Upon the death of King-Stadtholder William III,his heir,in The Netherlands became Prince Johan Willem Friso,Prince of Nassau Dietz,and Orange(1702)son of Willem Frederik of Nassau Dietz and Albertine Agnes,Princess of Orange Nassau,she herself a daughter of Frederick Hendrik and Amalia of Solms.Unfortunately Friso drowned in 1711,aged 24,his wife Marie Louise of Hesse-Cassel was pregnant with their son Willem IV.
Prince Willem IV married Princess Anna,Princess of Oarnge Nassau,néé of Great Britain and Hanover,Princess Royal in 1734.
Their daughter,Princess Caroline of Orange Nassau married Karl Christiaan of Nassau Weilburg,their grandson Adolph,(1817-1905)became GrandDuke of Luxembourg in 1890 upon the death of King Willem III.
Prince Willem V Batavus married Wilhelmina of Orange Nassau,néé of Prussia in 1767
Prince Willem I Frederik,Prince of the Netherlands 1772-1843 *married his cousin,Princess Frederika Louise Wilhelmina of Orange Nassau,Queen of the Netherlands,néé of Prussia.Sovereign Lord of The Netherlands 1813-1815,King Willem I 1815-1840(he abdicated)his daughter:
Princess Marianne of Orange Nassau,Princess of The Netherlands 1810-1883,married 1830,divorced 1849 her cousin Albrecht of Prussia.Her brother:
Prince Willem of The Netherlands(1792-1849) married Princess Anna of Orange Nassau,néé GrandDuchess of Russia in 1816,King Willem II and Queen Anna of The Netherlands 1840-1849.
his brother
Prince Frederik,married Princess Louise Augusta of Orange Nassau,néé of Prussia,their daughter
Princess Louise of Orange Nassau (1828-1871)married Karl XV of Sweden and Norway
Daughter Princess Marie of Orange Nassau(1841-1910) married Wilhelm of Wied,their son Wilhelm I became Sovereign of Albania.
to be continued