The Grand Duchy of Luxembourg had been a province of the Kingdom of the Netherlands since its foundation in 1815 before becoming independent but remaining in personal union with the Kingdom following the Treaty of London of 1839. It consisted of the territory of the duchy of Luxembourg, which had been a state of the Holy Roman Empire. Subsequently, the monarchs of the Netherlands were also Grand Dukes of Luxembourg.
The succession in Luxembourg was dictated by the Nassau family pact of 1793 and although King William III had attempted to change it to secure Luxembourg for Wilhelmina, it was Emma who convinced him not to do it. The Nassau family pact stipulated that Luxembourg would go from the Ottonian branch to the Walramian branch of the Nassau family if the Ottonian branch died out in the male line – which it did with King William III’s death in 1890. The head of the Walramian branch of the family was Adolphe, Duke of Nassau – whose lands had been annexed by Prussia in 1866. Adolphe also happened to be Queen Emma’s uncle – being her mother’s elder half-brother. Emma convinced William that it would not be chivalrous towards their less fortunate family to change the pact now.1
On 23 November 1890, upon the death of King William III, his daughter Wilhelmina succeeded him as Queen of the Netherlands while Adolphe became Grand Duke of Luxembourg.
In any case, Adolphe’s son William did not have any sons of his own and he named his elder daughter Marie-Adélaïde as heiress presumptive in 1907. This too had been arranged for in the Nassau family pact in the case both lines died out without male heirs and thus fulfilled this clause. The current Grand Duke of Luxembourg is the grandson of Marie-Adélaïde’s sister Charlotte, who succeeded her in 1919.
Luxembourg introduced absolute primogeniture – where the elder child succeeds regardless of gender – in 2011.