Prince Frederick William Adolf[note 1] of Nassau-Siegen (20 February 1680 – 13 February 1722), German: Friedrich Wilhelm Adolf Fürst von Nassau-Siegen, official titles: Fürst zu Nassau, Graf zu Katzenelnbogen, Vianden, Diez, Limburg und Bronkhorst, Herr zu Beilstein, Stirum, Wisch, Borculo, Lichtenvoorde und Wildenborch, Erbbannerherr des Herzogtums Geldern und der Grafschaft Zutphen, was since 1691 Fürst of Nassau-Siegen, a part of the County of Nassau.

He shared the city of Siegen with his second cousins, John Francis Desideratus (until 1699) and William Hyacinth (since 1699), the Catholic Fürsten of Nassau-Siegen.

In 1695, a major city fire destroyed a large part of Siegen, including the Nassauischer Hof, the princely Residenz, and the nearby church.

Numerous valuable paintings by famous artists, including Rembrandt, Peter Paul Rubens and Anthony van Dyck, fell victim to the flames.

[9][11] Frederick William Adolf devoted all his energy to governmental affairs and the reconstruction of the city of Siegen and the new palace (for which the plans were still the work of Fürst John Maurice and his Dutch architects Pieter and Maurits Post).

As a special honour, however, the magistrate had engaged the city pipers from Cologne for the festive reception, who certainly played at the dinner and the ball.

Complaints about this and about the unbearable burden of the tax rate, as well as about completely nonsensical regulations which paralysed economic life in Siegerland, finally led the Aulic Council to order the Electoral Palatinate to investigate the conditions in Nassau-Siegen.

On 15 July 1706, dragoons from Palatinate-Neuburg suddenly entered Siegen, together with a detachment of Prussian troops and 500 men of the Ausschuß of the Duchy of Berg.

The subjects of William Hyacinth were particularly annoyed by an edict proclaimed on 8 November 1706, according to which anyone who had a fortune and could pay the taxes but did not, had to have their heads cut off.

There he invited William II of Nassau-Dillenburg and Francis Alexander of Nassau-Hadamar and pointed out to them what it could mean if a Nassau area were to fall permanently under the administration of the Archdiocese of Cologne.

The cohesion within the House of Nassau was so great that the relatives even promised their support to such an incompetent man as William Hyacinth in order to regain governmental power.

The latter did not accept the offer because everyone could foresee that the Catholic line of Nassau-Siegen sooner or later would become extinct without male heirs and that the part of the land would fall to the Protestant relatives anyway.

In the light of a strong flashlight one could see that in the niche of Frederick William Adolf, at the foot of the very well preserved coffin, there is a box of about 60x40x40 cm, made of zinc or lead.

[24] Frederick William Adolf married at Homburg Castle[8][25] on 7 January 1702[6][25][26][note 4] to Landgravine Elisabeth Juliana Francisca of Hesse-Homburg (Homburg Castle,[28] 6 January 1681[4][note 5] – Nassauischer Hof, Siegen,[28] 12 November 1707[20]), the fifth daughter of Landgrave Frederick II of Hesse-Homburg and his second wife Duchess Louise Elisabeth of Courland.