Frederick William IV of Prussia
He continued the reactionary policies started by his father. During the Revolutions of 1848, the Frankfurt Congress offered him the Imperial Crown of Germany, but he turned it down, purportedly saying that he would not accept a crown from the gutter. In the following years, he became more and more mentally unstable: in 1858 his brother, Prince William became Regent. Frederick William died in 1861. As he had no children, his brother succeeded to the throne.
Frederick William III
List of Kings of Prussia|