King Willem II, King of the Netherlands, Grand Duke of Luxembourg, and Duke of Limburg

William II (Dutch: Willem Frederik George Lodewijk, anglicized as William Frederick George Louis; 6 December 1792 – 17 March 1849) was King of the Netherlands, Grand Duke of Luxembourg, and Duke of Limburg.

William II was the son of William I and Wilhelmine of Prussia. When his father, who up to that time ruled as sovereign prince, proclaimed himself king in 1815, he became Prince of Orange as heir apparent of the Kingdom of the Netherlands. With the abdication of his father on 7 October 1840, William II became king. During his reign, the Netherlands became a parliamentary democracy with the new constitution of 1848.

William II was married to Anna Pavlovna of Russia. They had four sons and one daughter. William II died on 17 March 1849 and was succeeded by his son William III. 

He entered the British Army, and in 1811, as a 19-year-old aide-de-camp in the headquarters of Arthur Wellesley, 1st Duke of Wellington, was allowed to observe several of Wellington's campaigns of the Peninsular War. Though not yet 20, the young prince, according to the customs of the time, was made lieutenant colonel on 11 June 1811^[10] and colonel on 21 October that year.^[11] On 8 September 1812 he was made an aide-de-camp to the Prince Regent^[12] and on 14 December 1813 promoted to major-general.^[13] His courage and good nature made him very popular with the British, who nicknamed him "Slender Billy". He returned to the Netherlands in 1813 when his father became sovereign prince, and in May 1814 succeeded Sir Thomas Graham as the highest-ranking officer of the British forces stationed there.^[14]

On 8 July 1814, he was promoted to lieutenant-general in the British Army,^[15] and on 25 July to general.^[16] As such, he was senior officer of the Allied army in the Low Countries when Napoleon I of France escaped from Elba in 1815. He relinquished command on the arrival of the Duke of Wellington, and, though this was his first real battle, served as commander of the I Allied Corps, first at the Battle of Quatre Bras (16 June 1815) and then at the Battle of Waterloo (18 June 1815), where he was wounded^[17] in his left shoulder by a musket ball.^[18] He was aged 22. As a sign of gratitude for what the Dutch throne styled "his" victory at Waterloo, William was offered Soestdijk Palace by the Dutch people.^[19][20]

Military historian William Siborne blamed many casualties suffered by Coalition forces during the Waterloo Campaign to William's inexperience.^[21] In response, Siborne was accused by Lieutenant-General Willem Jan Knoop of misrepresenting William's actions at Waterloo.^[22] An inspection into the archives of Siborne by Dutch officer Francois de Bas in 1897 claimed to discover the "selective use of sources" and "numerous miscounts and untruths".

On 7 October 1840, on his father's abdication, he acceded to the throne as William II. Although he shared his father's conservative inclinations, he did not intervene in governmental affairs nearly as much as his father had. There was increased agitation for broad constitutional reform and a wider electoral franchise. Although William was certainly no democrat, he acted with sense and moderation.

The Revolutions of 1848 broke out all over Europe. In Paris the Bourbon-Orléans monarchy that had stolen "his" southern provinces fell. Warned that the revolution might spread to the Netherlands next, William decided to institute a more liberal regime, believing it was better to grant reforms instead of having them imposed on him on less favourable terms later. As he later put it, "I changed from conservative to liberal in one night". He chose a committee headed by the prominent liberal Johan Rudolf Thorbecke to create a new constitution.

The new document provided that the Eerste Kamer (Senate), previously appointed by the King, would be elected indirectly by the Provincial States. The Tweede Kamer (House of Representatives), previously elected by the Provincial States, would be elected directly via census suffrage in electoral districts, with the franchise limited to those who paid a certain amount in taxes. Ministers were now fully responsible to the Tweede Kamer. For all intents and purposes, the real power passed to the Tweede Kamer, and the king was now a servant of government rather than its master. That constitution of 1848, amended numerous times (most notably by the replacement of census suffrage by universal manhood suffrage and districts with nationwide party-list proportional representation, both in 1917) is still in effect today.

He swore in his first and only cabinet under the terms of the new constitution a few months before his sudden death in Tilburg, North Brabant (1849).