William IV (Willem Karel Hendrik Friso; 1 September 1711 – 22 October 1751) was Prince of Orange from birth and the first hereditary stadtholder of all the United Provinces of the Netherlands from 1747 until his death in 1751.

Early life

William was born in Leeuwarden, Netherlands, the posthumous son of John William Friso, Prince of Orange, head of the Frisian branch of the House of Orange-Nassau, and of his wife Landgravine Marie Louise of Hesse-Kassel (or Hesse-Cassel). He was born six weeks after the death of his father.

William succeeded his father as Stadtholder of Friesland and also, under the regency of his mother until 1731, as Stadtholder of Groningen. In 1722 he was elected Stadtholder of Guelders. The four other provinces of the Dutch Republic—Holland, Zeeland, Utrecht and Overijssel—had in 1702 decided not to appoint a stadtholder after the death of stadtholder William III, ushering the Republic into a period that is known as the Second Stadtholderless Period. In 1747 those four provinces also accepted William as their stadtholder.

Marriage and children

In 1733, William was made a Knight of the Order of the Garter. On 25 March 1734, he married at St James's Palace Anne, Princess Royal, eldest daughter of King George II of Great Britain and Caroline of Ansbach. They had three children:

  • Princess Carolina of Orange-Nassau (28 February 1743 – 6 May 1787), married Karl Christian of Nassau-Weilburg
  • Princess Anna of Orange-Nassau (15 November 1746 – 29 December 1746) died in infancy.
  • William V, Prince of Orange (8 March 1748 – 9 April 1806), married Princess Wilhelmina of Prussia

Later life

In 1739 William inherited the estates formerly owned by the Nassau-Dillenburg branch of his family, and in 1743 he inherited those formerly owned by the Nassau-Siegen branch of his family.

thumb|left|upright|Portrait bust of William by [[Jan Baptist Xavery, 1733]]

thumb|left|upright|Portrait of William by an unknown artist, 1750

In 1740, the War of the Austrian Succession broke out. The conflict pitted Austria against France over the issue of whether Maria Theresa had the right to inherit her father Emperor Charles VI's crown. The Dutch Republic sided with Austria in 1747 in order to maintain a buffer zone between itself and France, whereupon French troops invaded the Austrian Netherlands. In a few weeks, Louis XV's troops conquered most of the towns in the Austrian Netherlands where the Dutch had stationed troops under the Barrier Treaty, as well as the most important towns in Zeelandic Flanders. The Dutch Republic was at the time weakened by internal division. The Dutch decided that their country needed a single strong executive, and turned to the House of Orange.