William I

William I treated Luxembourg not as an independent state but as a province of his kingdom. In Belgium, his policies caused deep dissatisfaction since they ignored the political, economic, and religious specificities of the southern provinces. In August 1830, the Belgian Revolution broke out, and by October, the Luxembourgers had joined the movement.
Their grievances against William I were numerous: heavy taxation, his blatant disinterest in Luxembourg, the fact that he visited only once (in Arlon), the appointment of foreigners to all high administrative positions, and his plan to introduce Dutch as a compulsory subject in primary schools. By rebelling, Luxembourgers hoped to free themselves from Dutch domination and to have their autonomy respected in the future.
Through the Treaty of London, the great powers recognized Belgium’s independence and imposed the partition of Limburg and Luxembourg. In 1839, William finally signed the treaty, acknowledging both the division and Luxembourg’s independence. However, the personal union with the Netherlands and Luxembourg’s membership in the German Confederation were confirmed.

William II

In 1840, William II succeeded his father and granted the Grand Duchy its own constitution. Although his reign was short, it was marked by important reforms. He established administrative structures that allowed Luxembourg to evolve into a true state and approved, in 1842, the country’s accession to the Zollverein (customs union with Prussia).
In 1848, Luxembourg adopted a very liberal constitution, significantly limiting royal prerogatives. William II died the following year, in 1849. In recognition of his achievements, an equestrian statue was erected in his honor in 1884, in the center of Luxembourg City.

William III

In 1849, his son William III ascended to the throne and reigned until 1890. More conservative in spirit, he found the constitution too liberal and too “republican.” In 1856, he ordered a constitutional revision that restored monarchical privileges, notably through the creation of a Council of State whose members were appointed by the sovereign.
He named his brother Henry as lieutenant-representative, who somewhat softened the king’s policies by defending Luxembourg’s independence abroad, especially during the 1867 crisis, when Napoleon III sought to purchase Luxembourg. William III died on November 23, 1890.
According to the House of Nassau Family Pact of 1783, the grand-ducal crown then passed to the only male heir of the Nassau line, Duke Adolph of Nassau-Weilburg. In the Netherlands, however, William III’s eldest daughter, Wilhelmina, succeeded him, as a different rule of succession applied there. This divergence brought an end to the personal union between Luxembourg and the Netherlands.