In 1659, Frederick was made governor of the household of his nephew, William III of Orange.
Through lobbying by Johan de Wit, William III became the state's ward in 1666, and Frederick was dismissed.
In April 1672 (the rampjaar) he became general of the infantry and in August he became involved in the murders of Johan and Cornelis de Wit.
On 16 October 1648, Frederick married Mary Killigrew (born 1627) in The Hague.
She was a first cousin of Charles II's illegitimate daughter, the Countess of Yarmouth.