Ivan 3 finally threw off the Tartar yoke. He was helped by the fairly recent split of the Golden Horde into separate khanates - Kazan, Crimea, Astrakhan and Siberia. He also had the advantage of the new technology of firearms against the bows and arrows of the Tartars.
He was married twice. His first marriage was to Princess Maria of Tver, who he married when he was 12 - the marriage produced a son and a grandson, Dimitri. His second marriage, to Sofia, produced a son Vasili, and the stage was set for disputes over the succession.
Initially Ivan sided with Dimitri. A boyar conspiracy came into being in favor of Vasili - when it was discovered, Ivan had several of Vasili’s friends beheaded on the frozen river and his second wife, Sofia, was imprisoned. A few weeks later, Dimitri was crowned as Tsarevitch.
A few years later, by 1499, as a result of Sofia's machinations, he came to believe he had been duped over the existence of a conspiracy. He beheaded a boyar who had opposed Vasili and imprisoned others. He handed his favor over to Vasili.
His second wife was the niece of the last emperor of Byzantium, Constantine 11 (and was originally named Zoe). This match strengthened the myth of Moscow and the Orthodox Church being a natural successor to the recently defunct Byzantine Empire as the seat of the Orthodox church.
In 1476, he stopped paying tribute to the Mongols, the extent of Muscovy quadrupled in size, and instituted a major building program in Moscow to confirm Moscow's elevated status.
The Uspessky cathedral was built in stone, followed by other churches and palaces - a major departure from the mostly wooden buildings of the city. He brought the architect Fioravanti to the city, and then Marco Ruffo, Pietro Solari and Alevisio Novi.
In 1480, he lost his nerve in his struggle against the Mongols, but it appears that the Mongol chief lost his almost simultaneously.
He adopted St. George and the Dragon as the emblem of Moscow (or the state of Muscovy to be more precise).
