On February 25th, Grand Duke Henri and Grand Duchess Maria Teresa will visit the German town of Weilburg to honour the Grand Duke's ancestors. Their are two ceremonial occasions for their visit to the small town in Hesse: on the one hand the 100th anniversary of the death of Grand Duke Wilhelm IV or Guillaume IV, it depends whether you prefer the German or French version of his name, and on the other hand the unveiling of a statue of Grand Duke Adolphe, Wilhelm's father.
[Caution, history lesson ahead!] As you may know, Henri is not only the Grand Duke of Luxembourg but also the titular Duke of Nassau. Since a couple of years the grand ducal family bears the last name de Nassau, before it was only Nassau. The branch of the House of Nassau the grand ducal family descends from is the Nassau-Weilburg line, though only through a female ancestor, namely Grand Duchess Charlotte.
As the name says it, the House of Nassau-Weilburg is named after the little Hessian town and members of the family ruled the Duchy of Nassau until 1866 when it was annexed by Prussia. In 1890 the former Dukes of Nassau became Grand Dukes of Luxembourg after Wilhelm III, who was both King of the Netherlands and Grand Duke of Luxembourg as well as head of the House of Orange-Nassau, failed to produce a male heir. His daughter Wilhelma became Queen of the Netherlands while the Grand Duchy was inherited by the distantly related Nassau-Weilburg family, due to different succession laws in the two countries: a case of salic law in Luxembourg versus semi-salic law in the Netherlands, meaning that in Luxembourg only females could ascend when the male line was totally extinct which it wasn't at the time.
In fact the male line of the House of Nassau became extinct exactly one hundred years ago when Grand Duke Wilhelm IV died. He had six daughters, among them two future Grand Duchesses, Marie-Adélaïde and Charlotte. So that his daughters could inherit the throne, Wilhelm declared the only male heir Count Georg Nikolaus of Merenberg, son of Prince Nikolaus of Nassau and his morganatic wife Natalia Pushkina, the daughter of Russian poet Alexander Pushkin, and his family to be non-dynastic.
Thus, Marie-Adélaïde inherited the throne aged 17 when her father died in 1912, for four months her mother acted as a regent. She was the first ruler of Luxembourg since about 700 years who was actually born in the Grand Duchy. After the first world war, Grand Duchess Marie-Adélaïde abdicated as she was highly unpopular because she was perceived as pro-German. In 1919, her sister Charlotte ascended to the throne and the same year more than 77% of Luxembourgers voted for a continuation of the monarchy under Charlotte. In the following years and especially during the second world war she became highly popular among her subjects and remained so until her death in 1985.
Grand Duke Henri is the sixth Grand Duke of Luxembourg coming from the House of Nassau-Weilburg, he predessors are Grand Duke Adolphe, Grand Duke Wilhelm IV, Grand Duchess Marie-Adélaïde, his grandmother Grand Duchess Charlotte and his father Grand Duke Jean. In fact he is only a cognatic descendant of the House of Nassau-Weilburg while agnatically he descends from the House of Bourbon-Parma through his grandfather Prince Félix of Bourbon-Parma.
This sometimes leads to a bit of confusion and the family is often called House of Nassau arisen from Bourbon-Parma or something similar, though they are not solely Bourbon-Parmas as the constitution of the Grand Duchy states that the head of states come from the House of Nassau so they have to be Nassaus. [Enough history for today.]
To kick off their one day stay in Weilburg, the grand ducal couple will be welcomed in the marketplace by the mayor before they inspect a guard of honour of the vigilante group of Nassau. Afterwards the guests from Luxembourg will make their way to Weilburg castle to take part in a mass in the church of the castle for Grand Duke Wilkelm IV, who died on February 25th, 1912. Interestingly, the crypt of the castle church is a Luxembourgish exclave. Shortly after the official program will continue in front of the mining and city museum to unveil a statue of Grand Duke Adolphe, before it ends with a visit to the auditorium of the Komödienhaus.
Source: Mittelhessen.de, Me