historical geographic location Belgium Netherlands United Kingdom of the Netherlands 1815 1839 https://en.wikipedia.org/wiki/United_Kingdom_of_the_Netherlands The unofficial name given to the Kingdom of the Netherlands as it existed between 1815 and 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. The polity was a constitutional monarchy, ruled by William I of the House of Orange-Nassau.