
Here's a complex question that requires someone to reason about the input, can you answer it?
Jonkheer Douwe Sirtema van Grovestins (Leeuwarden, Brussels, 1710 – February 26, 1778) was a Frisian courtier at the court of which stadtholder, that was the first hereditary Stadtholder of all the United Provinces?


William IV, Prince of Orange-Nassau
