Ivan VI, 1740–64, czar of Russia (1740–41), great-grandson of Ivan V. He was the son of Prince Anthony Ulric of Brunswick-Wolfenbüttel and of Anna Leopoldovna. An infant, he succeeded his great-aunt, Czarina Anna, on the Russian throne under the unpopular regency of his mother. In 1741, Elizabeth, daughter of Peter I (Peter the Great), overthrew Anna Leopoldovna's regime and became czarina. Ivan grew up in solitary confinement. An attempt by a young officer to liberate him and make him czar resulted in his murder in the fortress of Schlüsselburg, according to standing instructions given by Czarina Catherine II.