Principality of Nassau-Diez

In 1702, after the Glorious Revolution saw Prince William of Orange become King of England, the county was merged with others to form the new, larger, Principality of Orange-Nassau.

Nassau-Diez was created in 1386 when the former County of Diez was dissolved and taken over by the House of Nassau, though it was ruled by the Counts of Nassau-Dillenburg until 1606 when it became independent.

This line included not just the counts, but also served as Stadtholder of Friesland, Groningen, and Drenthe through the senior House of Orange-Nassau.

His eldest son Wilhelm "den Schweiger", who was originally a Lutheran, raised as a Roman Catholic from the age of 11, had inherited the county.

[1][3][4] The counties of Nassau-Dietz and Spiegelberg along with the Frisian governorship were then successively taken over by his sons Heinrich Casimir I and Wilhelm Friedrich.

Map of a large region (in white) including all the territory of modern Germany, Austria, Switzerland, Belgium and the Netherlands, plus parts of most neighbouring countries, including most of Northern Italy. Some of the northwest part region is highlighted in color, including Münster, most of the Netherlands and parts of modern Belgium.
The Lower Rhenish–Westphalian Circle (red) within the Holy Roman Empire (white) after 1548