The fall of Constantinople in 1453 allowed Ivan III (1462–1505) to style himself ‘tsar’, the natural successor to the emperors of Byzantium, and address the Holy Roman Emperor in correspondence as ‘brother’. Increasingly, his claims were justified. Although the Tatars were eliminated as a threat (the Crimean Khanate reached the gates of Moscow in 1519, during the reign of Vasili III, Ivan’s successor), they were increasingly marginalized, as were the unruly Boyar nobility, as both Ivan and Vassili ruthlessly centralized their rule. Ivan tripled the territory under his dominion, by conquest and marriage. He subjugated the Republic of Novgorod, advanced north to the White Sea, west to the Baltic (establishing the port of Ivangorod), and south into Lithuania. There was no respite under Vassili, who mopped up the remaining autonomous provinces such as Pskov, seized Smolensk from Lithuania, and finally subdued the Crimean Khanate in 1532.
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