Frederick William III

(born Aug. 3, 1770, Potsdam, Prussia—died June 7, 1840, Berlin) King of Prussia (1797–1840). The son of Frederick William II, he pursued a policy of neutrality in the early years of the Napoleonic Wars, which accelerated the decline of Prussia's prestige. Prussia joined the third coalition against France in 1806 and suffered crushing defeat at the Battles of Jena and Auerstedt. Defeat convinced the king of the need to make decisive changes. He allowed Prussian statesmen such as Karl August, prince von Hardenberg, and Karl, imperial baron vom Stein, to make domestic reforms, though the state remained absolutist. The Congress of Vienna confirmed Prussia's acquisition of Westphalia and much of Saxony, but the last 25 years of the king's reign brought a downward trend in Prussia's fortunes.

Source: Encyclopedia Britannica