Christian gave up his claim on Hesse-Wanfried-Rheinfels, in exchange for an annual pension of 7500 guilders, plus Eschwege Castle.
In 1718, the emperor put him in charge of Rheinfels Castle, where troops of Landgrave Charles of Hesse-Kassel had withstood and repulsed three heavy sieges by the French.
In 1719, William obtained permission from the Pope to revert to the lay state, to avert the impending extinction of the Hesse-Wanfried line.
After mediation by the Emperor, he married on 19 September 1719 with Ernestine, the daughter of Count Palatine Theodore Eustace of Sulzbach.
After William's death, Ernestine continued to live at Rheinfels Castle for a while, but then became prioress of the Carmelite monastery at Neuburg an der Donau, where she died on 5 April 1775.