With the succession of the Princess of Orange we'll see a first in Dutch Royal history. So far all 7 monarchs would have succeeded to the throne under every succession law the Kingdom has had (semi-Salic, male preferred and firstborn). Under the semi-Salic succession the line after King Willem-Alexander would go to either his brother prince Constantijn or nephew count Claus-Casimir of Orange-Nassau. They did mess things up a bit with Beatrix' sons and grandchildren.
His son William IV was the first to style himself Prince of Orange-Nassau.
By making the children of Friso and Constantijn part of the Dutch nobility their daughters can pass on the family name Van Oranje-Nassau van Amsberg to their offspring.
Count Claus-Casimir has a different position. Any of his children be it born in a marriage, outside a marriage or adopted will be count(ess) Van Oranje-Nassau, jonkheer/vrouwe Van Amsberg.
So Constantijn's male line will continue a noble line of the House of Orange-Nassau whereas Willem-Alexander's oldest daughter will continue the Royal House of Orange-Nassau. What will happen to the offspring of her younger sisters in anyone's guess at this moment. They might be counts or countesses of Orange-Nassau also or get a different style. We'll have to wait until Alexia and Ariane marry or announce a pregnancy.
Time and time again the Orange succession comes to the discussion.
For me, the house of Orange is extinct since the death of Q.Wilhelmina.
Genealogically speaking, Q.Juliana was a Mecklenburg, Q.Beatrix was a Lippe and K. Willem-Alexander is a von Amsberg, full stop.
It seems to me that in (semi-) salic successions, each time the male line fails, the headship of the house (etc) goes to an heiress nearest the last male/head or to her male line issue. In this instance, if we reckon René of Châlons as being of the "first" House of Orange then William the Silent was the first of the Second House of Orange (itself a cadet branch of the House of Nassau), Juliana was first and only head of the Third House of Orange (itself a cadet branch of the House of Mecklenburg), Beatrix was first and only head of the Fourth House of Orange (itself a cadet branch of the House of Lippe), and Willem-Alexander is head of the Fifth House of Orange (itself a branch of the House of Amsberg).
It is only after Willem-Alexander would things seem artificial to me according to the traditional modes of applying house names: W-A only has daughters yet he has brothers with issue. Everything up to this point is more or less "natural".
The Nassaus ?
Was the Nassaus non-opposition to the prestigious Orange title succession (not speaking of the succession to the dutch throne) part of the bargain that allowed GDk Adolphe to succeed in Luxembourg ?
I think the Dutch Royal Family up until this point have always had the better claim to Orange unless there were provisions in the Nassau Family Pact (which I don't fully understand) for it. The Luxembourgish Grand Ducal Family isn't descended from William the Silent in the male line, but they were the last male line of the original House of Nassau to go extinct so they are rightfully the heirs to Nassau. Orange, not having been in their line, goes to the Dutch Royal Family.
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