While the map of Europe changed, that of the Netherlands and Belgium stayed much the same during the rest of the Nineteenth century. In 1848 another European wide revolution failed, resulting only in local changes. One of these changes was the overthrow of conservative rule in the Netherlands. King William II gave his consent to a liberal constitution that survives, with significant changes, until this very day. France became a Republic once again and later an Empire under Napoleon III, second son of former King Louis I of Holland (see Benelux page on 1807) In Germany the war between Prussia and Austria in 1866 saw a great enlargement of Prussia. Schleswig-Holstein, Hanover, Hesse-Cassel, the city of Frankfurt and indeed the Duchy of Nassau were annexed to Prussia. The German Confederation was replaced by a North-German Confederation that would eventually grow into the German Realm of 1871 after the Franco Prussian War. The King of Prussia would become German Emperor, the remaining monarchies of Germany surviving as members of that Union.
Luxembourg had been placed outside of the German equation. Its independence was guaranteed by a number of powers, including the Netherlands, after Napoleon III tried to purchase it from Dutch King William III in 1866, almost causing a war between Prussia and France.
Limburg was in a peculiar position being at the same time a Dutch province and a Duchy, partly within the German Confederation. In 1867 when the North German confederation was founded, Limburg remained outside of it and Bismarck declared that Limburg was now free of its obligations towards the former member states of the German Confederation. The Dutch government ended Limburg’s special status as a Duchy, making it a normal province of the Netherlands, although the Dutch King and later Queens are called Dukes of Limburg to this very day.
With the death of King William III in 1890, the House of Orange-Nassau became extinct in the male line. His infant daughter Queen Wilhelmina succeeded to the throne of the Netherlands, but was barred from succeeding in Luxembourg, that was party to the 1777 Nassau House treaty, in which the different branches of the House of Nassau had agreed their succession arrangements. Luxembourg had taken the place of the Principality of Orange-Nassau (Nassau-Dietz) in these settlements, and thus a woman could not succeed there, being out ruled in favour of another male line descendant of one of the Nassau branches. Duke Adolph of Nassau, having lost his own country after the Austro-Prussian war of 1866, was thus made a sovereign once again when he succeeded as Grand duke of Luxembourg. Upon the death of his son Grand duke William IV in 1909 all branches of the House of Nassau were extinct in the male line. Luxembourg changed its dynastic law and William IV's daughter Marie-Adelaide became Grand duchess of Luxembourg.
The German Realm occupied Belgium during the First World War. The Netherlands succeeded in staying neutral. After the German defeat, the peace treaties of 1919 ceded the lands of Eupen and Malmedy and Sankt-Vith to Belgium. Belgium also received the neutral zink-mining region of Moresnet. These areas are roughly equivalent with parts of the pre Napoleonic Duchies of Limburg and Luxembourg as they were part of the Habsburg Netherlands in those days. Its annexation complicated the politics of multilingual Belgium, adding a German speaking community to the French and Dutch speaking communities already existing within Belgium.
Luxembourg was also occupied by the Germans in that war. The Netherlands that were obligated to come to Luxemburg’s defence in the settlement of 1866, refrained from doing so in fear of their cherished neutrality. The Grand duchess remained in the country and was blamed for not accepting the German occupation. The unmarried Grand duchess abdicated in favour of her sister Grand duchess Charlotte, and withdrew in a monastery where she died a few years later. The Belgians made an attempt at annexing Luxembourg but a plebiscite turned out in favour of Luxembourg's independence.
The fact that the Netherlands had allowed German troops to withdraw through their province of Limburg in 1918 caused great mayhem among the allies, especially Belgium. Belgium demanded reparations from the Netherlands in the form of South-Limburg and Zealand Flanders. None of this came about however and the frontiers of the three Benelux Nations have not changed much since.