In 1815, the collapse of the Napoleonic Empire resulted in a redrawing of the European map, which was to give rise to unexpected repercussions for Luxembourg.
With the aim of erecting a barrier against France, the great powers brought together at the Congress of Vienna decided to create a great Kingdom of the Netherlands. The new state included Holland, Liège and the former Austrian Netherlands. Logically, Luxembourg should also have been part of this territory.
But the diplomats thought differently. In fact, Luxembourg became a separate political entity. It was established as a grand duchy and assigned to the King of the Netherlands, William I of Orange-Nassau, who henceforth also bore the title of Grand Duke. The elevation in rank did not stop the country from losing a vast region situated to the east of the Moselle, the Sûre and the Our. These territories were awarded to Prussia. The Congress of Vienna brought about an additional complication regarding the international status of the Grand Duchy. The latter became a member of the German Confederation, an association of 39 German states essentially pledging mutual defence. The fortified town of Luxembourg thus became a federal fortress.
How can the resolutions adopted by the Congress of Vienna be explained? For one thing, the principle of monarchical legitimacy played a role. The Orange-Nassau dynasty was in possession of a number of small principalities in Westphalia which, in 1815, were absorbed by Prussia. William I received Luxembourg in compensation. This territory was awarded as a patrimonial asset, in contrast to the Kingdom of the Netherlands, which was not part of the heritage of the Orange-Nassau family. Furthermore, the diplomats doubted the ability of the Dutch to defend the fortress of Luxembourg. Integration into the German Confederation enabled a Prussian garrison to be stationed at the fortress, a far more efficient protection to contain a French attack. As a final shrewd touch, the title of Grand Duke gave William I precedence over the lesser German princes within the same Confederation.