United Kingdom of the Netherlands

The United Kingdom of the Netherlands is the unofficial but common historiographical name for the Kingdom of the Netherlands as it existed from 1815 to 1839. The United Netherlands was created in the aftermath of the Napoleonic Wars through the fusion of territories that had belonged to the former Dutch Republic, Austrian Netherlands, and Prince-Bishopric of Liège in order to form a buffer state between the major European powers. The polity was a constitutional monarchy, ruled by William I of the House of Orange-Nassau.

The polity collapsed in 1830 with the outbreak of the Belgian Revolution. With the de facto secession of Belgium, the Netherlands was left as a rump state and refused to recognise Belgian independence until 1839 when the Treaty of London was signed, fixing the border between the two states and guaranteeing Belgian independence and neutrality as the Kingdom of Belgium. Today, the Netherlands and Belgium are still kingdoms and Luxembourg is still a grand duchy and the only surviving grand duchy in the world.

In French, spoken by the southern residents, this state was officially referred to by a variant of the name Belgica, the Latin name for the entire region of the Low Countries, taken from the name of the Roman province Gallia Belgica. However, after the Belgian Revolution, in which the rebels took the name of Belgium for their new country, the rump (northern) Netherlands were given the name of the direct translation for Netherlands/Low Countries (Pays-Bas).