In 1814-1815, before the decrees of the Vienna Congress were known, an extraordinary attempt was made by Philippe d'Auvergne of the British navy, the cousin and adopted son of the last duke, to revive the ancient duchy of Bouillon.
In 1820 he retired with a pension his estate at Hornau, near Hochst, in Hesse-Darmstadt; but as a member of the first chamber of the states of the grand-duchy he continued to take an active share in the promotion of measures for the welfare of his country.
Weissenfels is a place of considerable antiquity, and from 1656 till 1746 it was the capital of the small duchy of Saxe-Weissenfels, a branch of the electoral house of Saxony, founded by Augustus, second son of the elector John George I.
Of Sweden, and conquered the duchy of Bremen.
In 1619 he received by bequest, ratified in 1620 by royal grant, the duchy of Angouleme.