This section is from "The American Cyclopaedia", by George Ripley And Charles A. Dana. Also available from Amazon: The New American Cyclopędia. 16 volumes complete..
Peter III, emperor of Russia, born in Kiel, Feb. 21, 1728, died at Ropsha, July 17, 1762. He was the son of the duke Charles Frederick of Holstein and of Anna Petrovna, a daughter of Peter the Great, and was first known as Duke Charles Peter Ulric of Holstein-Gottorp. According to the right of succession established by Peter the Great, he was designated in 1742 by the latter's daughter and his aunt, the empress Elizabeth Petrovna, as cesarovitch and successor to the throne; and he was also destined by her, at the suggestion of Frederick the Great, to become the husband of the princess of Anhalt-Zerbst, the future Catharine II. The marriage took place in September, 1745, but he led an unhappy life with Catharine. He ascended the throne on the death of Elizabeth, Jan. 5,1762, and immediately made peace and an offensive alliance with Frederick the Great, restoring to him the province of Prussia, which had been conquered by the Russians, and supplying him with an auxiliary army of 15,000 men. He was about to take the field against Denmark to enforce the claims of the house of Holstein-Gottorp upon Schleswig, when his wife usurped the throne (July 8-9), and he was deposed, arrested, and strangled in prison. (See Cathaeine II).
 
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