I. George, a Prussian diplomatist, born at Kincardine, Scotland, in 1685, died near Potsdam, Prussia, May 25, 1778. He was the tenth earl marischal, and the descendant of a race who had long been grand marischals of Scotland. Being outlawed and his estates confiscated for participation in the rebellion of 1715, he fled to Spain, and thence to Prussia, where he became a friend of Frederick the Great, who appointed him ambassador at Paris in 1751, governor of Neufchatel in 1754, and envoy to Madrid in 1759. His estates were subsequently restored to him, and he also inherited in 1761 the entailed estates of the earls of Kintore. He died unmarried, and his eldest sister, wife of the earl of Wigtown, transmitted the Keith title to her daughter, who married Lord Elphinstone, and was the mother of Admiral Keith. II. James, brother of the preceding, born in Scotland, June 11, 1696, killed at Hochkirch, Oct. 14, 1758. He was likewise attainted of high treason on account of the rebellion of 1715, fled to France, where he studied mathematics under Maupertuis, and was admitted to the academy.

In 1717 he went to Spain to serve the cause of the pretender, but the enterprise was unsuccessful, and he did not return to Madrid till 1720. He failed of obtaining employment, as he refused to abjure Protestantism. Subsequently he accompanied the duke of Leiria, the Spanish ambassador, to Russia, where he became a general, especially distinguishing himself in the war against Turkey (1736-7), and was severely wounded at thestorming of Otchakov. He afterward aided in the victories over the Swedes, and after the peace of Abo (1743) became Russian ambassador at Stockholm, and on his return to St. Petersburg was made field marshal. The service was made so irksome to him that he tendered his resignation, which was accepted on condition of his never fighting against Russia. He went to Hamburg (1747) and tendered his services to Frederick the Great, who grasped eagerly at the offer. He became governor of Berlin in 1749, and accompanied the king in many memorable campaigns, distinguishing himself on various occasions, especially in the retreat from Olmutz, and at Hochkirch. His success was the more remarkable as he was ignorant of the German language. - See Leben des Feldmarsclialls Jakob Keith, by Varnhagen von Ense (Berlin, 1844).