Karl August Vou Hardenberg, prince, a German statesman, born at Essenroda, Hanover, May 31, 1750, died in Genoa, Nov. 26, 1822. He received a brilliant education, travelled extensively abroad, and on his return to Hanover in 1778 entered the civil service. Shortly afterward he was sent on a diplomatic mission to London. The discovery of an intrigue between his wife and an English prince caused him to leave Hanover after having separated from her, and to enter the service of the duke of Brunswick. In 1786 he was deputed to deliver the will of Frederick the Great, which had been deposited with the duke, to his successor, Frederick William II. At that sovereign's recommendation he became in 1790 minister of the margrave of Anspach and Baireuth, at the time when the French actress Clairon, who had ruled the margrave and his people for 17 years, was supplanted in his affections by Lady Craven, who, however, could only be won by marriage. In 1791 Hardenberg effected the arrangement by which the territory of the margrave was ceded to Prussia, in consideration of a large annuity, which enabled that prince to reside with Lady Craven in affluence in England, and Hardenberg was made minister of state and governor of the ceded provinces.

After the breaking out of the war with France in 1792, the king appointed him administrator of the army, and in 1795, as an ambassador for Prussia, he signed the treaty of peace at Basel. In 1797, on the accession of Frederick William III., he was intrusted with the direction of the affairs of Franconia. In 1804, after Berna-dotte's invasion of Hanover, Hardenberg became prime minister for a short time. His bold rebuke of Napoleon's invasion of the German territory irritated the emperor; and when the victory of Austerlitz and the treaty of Pres-burg, in December, 1805, had strengthened Napoleon's position, and humbled the power of Prussia, the king, through fear of war, sacrificed his minister, and Haugwitz was appointed in his stead. For a time Hardenberg continued in the ministry of foreign affairs, but Napoleon declared, July 4,1807, that he would not conclude the peace of Tilsit unless Hardenberg was dismissed, and the latter withdrew accordingly, and passed some time in exile in Russia. Returning to Berlin in 1810, he became chancellor of state, and carried out with zeal the policy of reforms shortly before inaugurated by Stein. Permission was granted to citizens and agricultural laborers to acquire and possess real estate, and to the nobles to engage in industrial and commercial pursuits without prejudice to their dignity.

The burdens which hitherto lay exclusively upon the humbler classes were removed, the estates of the clergy were appropriated for the liquidation of the public debts, new resources were developed for the replenishment of the exhausted treasury, the army was reorganized, a new and improved system of national education was introduced, and harmony was restored between king, nobles, and people by an equal distribution of taxes and privileges. Finally, serfdom was abolished. Hardenberg aided powerfully in rousing the enthusiasm of the Germans in 1813 against Napoleon, signed the treaty of peace in 1814 as the representative of Prussia, and in reward for his services was raised to the rank of prince (June 3), and presented with the rich domain of Neuhardenberg. He accompanied the allied sovereigns to London, attended the congress of Vienna, and took part in the treaties of Paris in 1815. In 1817 he organized the council of state, of which he became president, and was present on behalf of Prussia at the congresses of Troppau, Laybach, and Verona (1820-'22). In the latter part of his administration he reformed the system of taxation, and regulated the national archives.

He left memoirs of his times from 1801 to the peace of Tilsit, which were deposited in the national archives, not to bo opened until 50 years after his death. The Memoires d'un homme d'etat (Paris, 1828; German, Leipsic, 1828), containing some of his despatches, has been erroneously ascribed to him; Alphonse de Beauchamp is supposed to be the author. His biography was published by Klose in Halle in 1851.