as the most influential, largely due to decisions made by the Mongol khan; aside from this, the metropolitan bishop of Rus’ started to be based in Moscow too. Yuriy's successor, Ivan I (ruled 1325–1340), managed to retain the title of Grand Duke by cooperating closely with the Mongols and by collecting tribute and taxes from other Rus' principalities on their behalf. This relationship enabled Ivan to gain regional ascendancy, particularly over Moscow's chief rival, the northern city of Tver, which rebelled against the Horde in 1327. The uprising was subdued by the joint forces of the Grand Duchy of Suzdal, the Grand Duchy of Moscow (which competed with Tver for the title of the Grand Duke of Vladimir), and Tatars. Ivan was reputed to be the richest person in Rus', as his moniker "Kalita" (literally, the "moneybag") testifies. He used his treasures to purchase land in other principalities and to finance the construction of stone churches in the Moscow Kremlin. In 1325 the Orthodox Metropolitan Peter (died 1326) transferred his residence from Kiev to Vladimir and then to Moscow, further enhancing the prestige of the new principality. Dmitri Donskoi Ivan's successors continued gathering the lands of Rus' to increase the population and wealth under their rule. In the process, their interests clashed with the expanding Grand Duchy of Lithuania, whose subjects were predominantly East Slavic and Orthodox. Grand Duke Algirdas of Lithuania allied himself by marriage with Tver and undertook three expeditions against Moscow (1368, 1370, 1372) but was unable to take it. The main bone of contention between Moscow and Vilnius was the large city of Smolensk. In the 1350s, the country and the royal family were hit by the Black Death. Dmitry Ivanovich was aged nine when his parents died and the title of Grand Duke slipped into the hands of his distant relative, Dmitry of Suzdal. Surrounded by Lithuanians and Muslim nomads, the ruler of Moscow cultivated an alliance with the Rus' Orthodox Church, which experienced a resurgence in influence, due to the monastic reform of St. Sergius of Radonezh. Educated by Metropolitan Alexis, Dmitri posed as a champion of Orthodoxy and managed to unite the warring principalities of Rus' in his struggle against the Horde. He challenged Khan's authority and defeated his commander Mamai in the epic Battle of Kulikovo (1380). However, the victory did not bring any short-term benefits; Tokhtamysh in 1382 sacked Moscow hoping