Born posthumously on 1 September 1711 in Leeuwarden, he was baptised there nine days later. In Friesland his mother was Regent for him until 1731. During his long minority the 'Regents' in Holland did all they could to reduce the power of the Stadhouder. The main force was the province of Holland and the other provinces followed their lead. As a result he remained Stadhouder of Friesland only until 1728 when he was accepted by Groningen, then in 1722 by Drente and Gelderland.
In 1729 he visited The Hague for the first time but was given rather a cool reception. On 25 March 1734 in London he married Anna of Hanover, daughter of King George II of Great Britain. First they had two stillborn daughters and then Carolina, born in 1743, who survived; Anna in 1746 who died a month later; and Willem V born in 1748.
In 1739 he inherited the family estates of Nassau-Dillenburg and in 1743 those of Nassau-Siegen. In April 1747 the French entered Flanders and as a result Willem IV was appointed Stadhouder and 
Captain-General of all The Netherlands. The Prince and his family left Leeuwarden and moved to The Hague. Sadly he had previously been left out of state affairs and had no-one to guide him, even though
leadership was expected of him.
He allowed the Regents to remain in their position by which he earned the gratitude of at least some. However, he did stop some mercenary practices, such as positions being sold within the oligarchie but with someone else being expected to do the work for only part of the attached salary. He also stopped indirect taxation, removing the contractors who raked in extra money for themselves.
All through these actions of trying to reduce the power of the Regents he kept his wife informed. One of his main supporters was Willem Bentinck, a son of the Earl of Portland. Moreover he also found
himself supported by the population of the provinces which further strengthened his position.
From 1747 onwards he worked very hard and, according to some, involved himself in too much detail which affected his health. In 1751 he took a cure which at first appeared to have worked, but he died on 22 October 1751.

Source: Leo van de Pas