to reassert his vested authority over his vassal, the Grand Prince, and his own Mongol hegemony, killing 24,000 people. Nevertheless, Dmitri became a national hero. The memory of Kulikovo Field made the Rus' population start believing in their ability to end Tatar domination and become a free people. In 1389, he passed the throne to his son Vasily I without bothering to obtain the Khan's sanction. Vasily I and Vasily II Vasily I (1389–1425) continued the policies of his father. After the Horde was attacked by Tamerlane, he desisted from paying tribute to the Khan but was forced to pursue a more conciliatory policy after Edigu's incursion on Moscow in 1408. Married to the only daughter of the Grand Duke Vytautas of Lithuania, he attempted to avoid open conflicts with his powerful father-in-law, even when the latter annexed Smolensk. The peaceful years of his long reign were marked by the continuing expansion to the east (annexation of Nizhny Novgorod and Suzdal, 1392) and to the north (annexation of Vologda, Veliky Ustyug, and Perm of Vychegda, 1398). Nizhny Novgorod was given by the Khan of the Golden Horde as a reward for Muscovite help against a rival. The reforms of St. Sergius triggered a cultural revival, exemplified by the icons and frescoes of the monk Andrei Rublev. Hundreds of monasteries were founded by disciples of St. Sergius in distant and inhospitable locations, including Beloozero and Solovki. Apart from their cultural functions, these monasteries were major landowners that could control the economy of an adjacent region. In fact, they served as outposts of Moscow influence in the neighboring principalities and republics. Another factor responsible for the expansion of the Grand Duchy of Moscow was its favorable dynastic situation, in which each sovereign was succeeded by his son, while rival principalities were plagued by dynastic strife and splintered into ever-smaller polities. The only lateral branch of the House of Moscow, represented by Vladimir of Serpukhov and his descendants, was firmly anchored to the Moscow Duchy. The situation changed with the ascension of Vasily I's successor, Vasily II (r. 1425–62). Before long his uncle, Yuri of Zvenigorod, started to advance his claims to the throne and Monomakh's Cap. A bitter family conflict erupted and rocked the country during the whole reign. After Yuri's death in 1432, the claims were taken up by his sons, Vasily Kosoy and Dmitry Shemyaka, who pursued the Great Feudal