[1] On 18 April 1806, Friedrich Wilhelm joined the Prussian Army by entering the Gardes du Corps regiment and from the next year participated in the Napoleonic War of the Fourth Coalition.

In 1812 he achieved the rank of Rittmeister in the staff of Ludwig Yorck von Wartenburg, leading the Prussian auxiliary forces in support of the French invasion of Russia.

During the German revolutions of 1848–49, in November 1848, his half-nephew King Frederick William IV called him back to Berlin to succeed Ernst von Pfuel as Prussian minister president.

Jointly with Interior Minister Otto Theodor von Manteuffel, he had the Prussian National Assembly dissolved on 5 December, while on the same day the King unilaterally decreed a Constitution that kept the monarch firmly in control but that also included a catalog of fundamental rights and a parliament with a second chamber elected under universal manhood suffrage.

Though he had initially supported the implementation of the Prussian-led Erfurt Union, he shied away from an armed conflict with Austria as State Chancellor Prince Felix of Schwarzenberg was able to strengthen the alliance with the Russian Empire isolating the Prussian side.