Wilhelm was joint sovereign Duke of Nassau, along with his father's cousin Frederick Augustus, reigning from 1816 until 1839. He was also sovereign Prince of Nassau-Weilburg from 1816 until its incorporation into the duchy of Nassau.

Kirchheimbolanden, the capital of Donnersbergkreis, is a town in Rhineland-Palatinate, south-western Germany. It is situated approximately 25 km west of Worms, and 30 km north-east of Kaiserslautern. The first part of the name, Kirchheim, dates back to 774. It became a town in 1368, and the Sponheim family improved its security with many towers and walls. William, Duke of Nassau, ancestor of the royal families of Belgium, Sweden, Denmark and Norway, and of the grand-ducal family of Luxembourg, was born in Kirchheimbolanden. It was also ruled by the First French Empire between 1792 and 1814, before passing to the Kingdom of Bavaria in 1815. It was a rural district centre in the Rheinkreis, which was renamed Pfalz (Palatinate) in 1835.