Peter III and Adoption
Peter was the son of Duke Charles Frederick of Holstein-Gottrop and Anna, the daughter of Czar Peter the Great and was born in Kiel, Germany.
He was adopted by the Empress Elizabeth Petrovna, his aunt, and succeeded her on her death. He became czar in 1761 during a war with Prussia, which he immediately stopped, thus sacrificing the gains made by Russia during the Seven Years' War. This antagonized the Russian nobility, and he was deposed, and then assassinated on 7 July 1762. In this the nobility had the backing of the czarina, who ascended the throne as Catherine the Great.
One of his few reforms during his short reign was to stop the persecution of dissenting non-Orthodox Christians.
Microsoft Encarta 98 Encyclopedia, 1993-97 Levykin, Alexei K. "Peter III (Peter Feodorovich)." Available at: www.sptimes.com/Treasures/TC.2.3.12.html