Russian Empire
Though the Empire was only officially proclaimed by Tsar Peter I following the Treaty of Nystad (1721), some historians would argue that it was truly born either when Ivan III of Russia conquered Veliky Novgorod in 1478, or when Ivan the Terrible conquered the Khanate of Kazan in 1552. According to another point of view, the term "Tsardom", which was used after the coronation of Ivan IV in 1547, was already a contemporary Russian word for empire.
Russian Empire
Empress Catherine the Great (reigned 1762–1796) presided over a golden age; she expanded the state by conquest, colonization and diplomacy, continuing Peter the Great's policy of modernization along Western European lines. Emperor Alexander II (1855–1881) promoted numerous reforms, most dramatically the emancipation of all 23 million serfs in 1861. His policy in Eastern Europe involved protecting the Orthodox Christians under the rule of the Ottoman Empire. That connection by 1914 led to Russia's entry into the First World War on the side of France, the United Kingdom, and Serbia, against the German, Austrian, and Ottoman empires.