Passage: By late 1848, the Prussian aristocrats and generals had regained power in Berlin. They had not been defeated permanently during the incidents of March, but had only retreated temporarily. General von Wrangel led the troops who recaptured Berlin for the old powers, and King Frederick William IV of Prussia immediately rejoined the old forces. In November, the king dissolved the new Prussian parliament and put forth a constitution of his own which was based upon the work of the assembly, yet maintaining the ultimate authority of the king.

Question: What was the name of the King of Prussia in 1848?
King Frederick William IV