The House of Nassau is a diversified aristocratic dynasty in Europe. It is named after the lordship associated with Nassau Castle, located in present-day Nassau, Rhineland-Palatinate, Germany. The lords of Nassau were originally titled Count of Nassau, then elevated to the princely class as princely counts. At the end of the Holy Roman Empire, they proclaimed themselves Dukes of Nassau.
All Dutch queens since 1890 and the Grand Dukes of Luxembourg since 1912 have been descended in the female line from the House of Nassau. According to German tradition, the family name is passed only in the male line of succession. The house is therefore, from this perspective, extinct since 1985[1]. However Dutch aristocratic customs (and Luxembourg's, which are based on the aforementioned) differ, and do not consider the House extinct.
Count Dudo-Henry of Laurenburg (ca. 1060 - ca. 1123) is considered the founder of the House of Nassau. He is first mentioned in the purported founding-charter of Maria Laach Abbey in 1093 (although many historians consider the document to be fabricated). The Castle Laurenburg, located a few miles upriver from Nassau on the Lahn, was the seat of his lordship. His family probably descended from the Lords of Lipporn. In 1159, Nassau Castle became the ruling seat, and the house is now named after this castle.
The Counts of Laurenburg and Nassau expanded their authority under the brothers Robert (Ruprecht) I (1123–1154) and Arnold I of Laurenburg (1123–1148). Robert was the first person to call himself Count of Nassau, but the title was not confirmed until 1159, five years after Robert's death. Robert's son Walram I (1154–1198) was the first person to be legally titled Count of Nassau.
The chronology of the Counts of Laurenburg is not certain and the link between Robert I and Walram I is especially controversial. Also, some sources consider Gerhard, listed as co-Count of Laurenburg in 1148, to be the son of Robert I's brother, Arnold I.[2] However, Erich Brandenburg in his Die Nachkommen Karls des Großen states that it is most likely that Gerhard was Robert I's son, because Gerard was the name of Beatrix of Limburg's maternal grandfather.[3]
In 1255, Henry II's sons, Walram II and Otto I, split the Nassau possessions. The descendants of Walram became known as the Walram Line, which became important in the Countship of Nassau and Luxembourg. The descendants of Otto became known as the Ottonian Line, which would inherit parts of Nassau, France and the Netherlands. Both lines would often themselves be divided over the next few centuries. In 1783, the heads of various branches of the House of Nassau sealed the Nassau Family Pact (Erbverein) to regulate future succession in their states.
Count Walram II began the Countship of Nassau-Weilburg, which existed to 1816. The sovereigns of this house afterwards governed the Duchy of Nassau until 1866 and from 1890 the Grand Duchy of Luxembourg. The branch of Nassau-Weilburg ultimately became rulers of Luxembourg. The Walram line received the lordship of Merenberg in 1328 and Saarbrücken (by marriage) in 1353.
In 1866, Prussia annexed the Duchy of Nassau as the duke had been an ally of Austria in the Second Austro-Prussian War. In 1890, Duke Adolf would become Grand Duke Adolphe of Luxembourg.
From a morganatic marriage, contracted in 1868, descends a family, see Count of Merenberg, which in 1907 was declared non-dynastic. Had they not been excluded from the succession, they would have inherited the headship of the house in 1912.
The branch of Nassau-Siegen was a collateral line of the House of Nassau, and ruled in Siegen. The first Count of Nassau in Siegen was Count Henry, Count of Nassau in Siegen (d. 1343), the elder son of Count Otto I of Nassau. His son Count Otto II of Nassau ruled also in Dillenburg.
In 1606 the House was separated from the House of Nassau-Dillenburg. After the main line of the House became extinct in 1734, Emperor Charles VI transferred the county to the House of Orange-Nassau.
The House of Orange-Nassau stems from the Ottonian Line. The second person was Engelbert I, who offered his services to the Duke of Burgundy, married a Dutch noblewoman and inherited lands in the Netherlands, with the barony of Breda as the core of the Dutch possessions.
The importance of the Nassaus grew throughout the 15th and 16th century. Hendrik III of Nassau-Breda was appointed stadtholder of Holland, Zeeland and Utrecht by Charles V, Holy Roman Emperor in the beginning of the 16th century. Henry was succeeded by his son, René of Châlon-Orange in 1538, who was, as his full name stated, Prince of Orange. When René died prematurely on the battlefield in 1544 his possessions and the princely title passed to his cousin, William the Silent, a Count of Nassau-Dillenburg. By dropping the suffix name "Dillenburg" (of the Orange-Nassau-Dillenburg), from then on the family members called themselves "Orange-Nassau."
With the death of William III, the legitimate direct male line of William the Silent became extinct and thereby the first House of Orange-Nassau. John William Friso, the senior agnatic descendant of William the Silent's brother and a cognatic descendant of Frederick Henry, grandfather of William III, inherited the princely title and all the possessions in the low countries and Germany, except the Principality of Orange itself. The Principality was ceded to France under the Treaty of Utrecht that ended the wars with King Louis XIV. John William Friso, who also was the Prince of Nassau-Dietz, founded thereby the second House of Orange-Nassau (the suffix name "Dietz" was dropped of the combined name Orange-Nassau-Dietz).
After the post-Napoleonic reorganization of Europe, the head of House of Orange-Nassau gained the title "King/Queen of the Netherlands".
Following German laws, the House of Orange-Nassau(-Dietz) is extinct since the death of Wilhelmina (1962), contradictory to Dutch laws.