United Kingdom of the Netherlands

The United Kingdom of the Netherlands is the historians' name for the Kingdom of the Netherlands as it stood from 1815 to 1839. It was made after the Napoleonic Wars by fusing the lands of the old Dutch Republic with the Austrian Netherlands and the Prince-Bishopric of Liège, to form a buffer state between the great powers of Europe, and the Congress of Vienna blessed the union. The polity was a constitutional monarchy under William I of the House of Orange-Nassau, who tried to rule Dutch and Belgians, Catholics and Protestants, French-speakers and Dutch-speakers as one people. It broke in 1830 with the Belgian Revolution: the southern provinces rose, Belgium seceded in fact, leaving the Netherlands a rump, which refused to recognise the break until the Treaty of London of 1839 drew the border and guaranteed the new Kingdom of Belgium its independence and neutrality. The Netherlands and Belgium remain kingdoms to this day, and Luxembourg, detached from the union, is still the world's only surviving grand duchy.