After the sudden death of Vasily I of Moscow, in the same year plague killed three Grand Dukes of Tver: Ivan Mikhailovich, Boris' father Aleksander Ivanovich and brother Yuri Aleksandrovich.

[citation needed] At the beginning of his reign the Muscovite prince Vasily II was very young, so the power was concentrated in hands of his warden Vytautas (Vitovt).

[3] During his reign, around or after 1453, the monk Foma (Thomas) of Tver wrote the Pokhval'noe slovo (похвальное слово) or Word of Praise for the Grand Prince Boris Aleksandrovich.

[4] It is alternately known as The Eulogy of the Pious Grand Prince Boris Alexandrovich, and has traditionally been interpreted as the origins of the idea of a Third Rome (after the 1453 Fall of Constantinople); although this ideology would later be associated with Moscow, it began in Tver.

[4][5][6] In 1977, Charles J. Halperin analysed that the Muscovite War of Succession weakened Muscovy so much that its old Tverian rival once again felt strong enough to challenge its sole claim to represent the "Rus' Land" (русская земля) in this Word of Praise.