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Ivan IV Vasilyevich (Russian: Ivan Vasil'evich, tr. Ivan Vasilyevich; 25 August 1530 - 28 March [O.S. 18 March] 1584), commonly known as Ivan the Terrible or Ivan the Fearsome (Russian:  Ivan Groznyi  , Ivan Grozny; a better translation into modern English

Ivan was the first son of Vasili III and his second wife, Elena Glinskaya, who was of half Serbian and half Lipka Tatar descent, the Glinski clan (nobles based in the Grand Duchy of Lithuania) claiming descent from the Mongol ruler Mamai (1335-1380.) When Ivan was three years old, his father died from an abscess and inflammation on his leg that developed into blood poisoning. Ivan was proclaimed the Grand Prince of Moscow at the request of his father. His mother Elena Glinskaya initially acted as regent, but she died of what many believe to be assassination by poison, in 1538 when Ivan was only eight years old. The regency then alternated between several feuding boyar families fighting for control. According to his own letters, Ivan, along with his younger brother Yuri, often felt neglected and offended by the mighty boyars from the Shuisky and Belsky families. In a letter to Prince Kurbski Ivan remembers, "My brother Iurii, of blessed memory, and me they brought up like vagrants and children of the poorest. What have I suffered for want of garments and food!!" It should be noted, however, that the historian Edward L Keenan has presented compelling reasons to doubt the authenticity of the source in which these quotes are found.  On 16 January 1547, at age sixteen, Ivan was crowned with Monomakh's Cap at the Cathedral of the Dormition. He was the first to be crowned as "Tsar of All the Russias", hence claiming the ancestry of Kievan Rus'. Prior to that, rulers of Muscovy were crowned as Grand Princes, although Ivan III the Great, his grandfather, styled himself "tsar" in his correspondence. Two weeks after his coronation, Ivan married his first wife Anastasia Romanovna, a member of the Romanov family, who became the first Russian tsaritsa.  By being crowned Tsar, Ivan was sending a message to the world and to Russia: he was now the only supreme ruler of the country, and his will was not to be questioned. "The new title symbolized an assumption of powers equivalent and parallel to those held by former Byzantine Emperor and the Tatar Khan, both known in Russian sources as Tsar. The political effect was to elevate Ivan's position." The new title not only secured the throne, but it also granted Ivan a new dimension of power, one intimately tied to religion. He was now a "divine" leader appointed to enact God's will, as "church texts described Old Testament kings as 'Tsars' and Christ as the Heavenly Tsar." The newly appointed title was then passed on from generation to generation: "succeeding Muscovite rulers ... benefited from the divine nature of the power of the Russian monarch ... crystallized during Ivan's reign."
Ivan the Terrible