Prince William IV (1711-1751)
Willem Karel Hendrik Friso was born in Leeuwarden in 1711, the son of Johan Willem Friso of Nassau-Dietz and Marie-Louise of Hesse-Kassel. In 1747, as Prince William IV, he became the first person to hold the office of stadholder in all seven provinces of the Dutch Republic.
After his father’s death he had become stadholder of Friesland, Groningen and Gelderland. Now, faced with the threat of another French invasion, the other provinces also appointed him stadholder.
During this same time, the office of stadholder was made hereditary in the House of Orange, in both the male and female line.
In 1734 William IV married Princess Anne of Hanover, daughter of King George II of Great Britain.
William IV could not use his increasing influence for long. His health deteriorated, and his wife took over responsibility for the affairs of state. When he died in 1751 his only son, Prince William V, was still a minor.