William II: King of the Netherlands and Grand Duke of Luxembourg from 1840 to 1849. Peninsular War: A military conflict between Napoleon's empire and the allied powers of Spain, Britain, and Portugal for control of the Iberian Peninsula during the Napoleonic Wars. Battle of Waterloo: A decisive battle in 1815 in which Napoleon was defeated by an alliance under the Duke of Wellington, marking the end of the Napoleonic Wars. Belgian Revolution: A conflict in 1830 leading to the secession of the southern provinces from the United Kingdom of the Netherlands and the establishment of Belgium. F.A. van Hall: Finance minister chosen by William II who helped stabilize the Dutch economy and achieve a budget surplus. Liberal monarchy: A form of monarchy with a constitution limiting the powers of the king and expanding the rights of the citizens.