Neutral Moresnet was a small Belgian–Prussian condominium in western Europe that existed from 1816 to 1921 and was administered jointly by the United Kingdom of the Netherlands and the Kingdom of Prussia. It was 1.5 kilometres (1 mi) wide and five kilometres (3 mi) long, with an area of 360 hectares. After 1830, the territory's northernmost border point at Vaalserberg connected it to a quadripoint shared additionally with the Dutch Province of Limburg, the Prussian Rhine Province, and the Belgian Liège Province. Its former location is represented presently by the Three-Country Point, the meeting place of the borders of Belgium, Germany, and the Netherlands.

The United Kingdom of the Netherlands is the unofficial name given to the Kingdom of the Netherlands as it existed between 1815 and 1830. 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.