Grand Prince of Moscow
Demetrios was born in 1350 and succeeded as Prince of Moscow as a child, later holding also the grand-princely dignity of Vladimir. Having lost his father young, he was raised under the care of Saint Alexis, Metropolitan of Moscow. The synaxarion recalls that he united Christian piety with notable gifts as a statesman, laboring both for the gathering of the Russian principalities and for their freedom from Tatar-Mongol rule.
During his reign Moscow grew in strength and standing. He raised the first stone walls of the Moscow Kremlin and founded monasteries, and his rule is remembered as a turning point in the consolidation of the Russian state around Moscow.
The Battle of Kulikovo
In 1380 Demetrios led the Russian princes against the army of Mamai, the ruler of the Tatar Horde. Before setting out he went to Saint Sergius of Radonezh for his blessing; the elder foretold his victory and sent with him two monks of his monastery, the schema-monks Alexander Peresvet and Andrew Oslyabya, to support the prince in the campaign.
On September 8, 1380, the feast of the Nativity of the Mother of God, the battle was joined on the field of Kulikovo between the Don and Nepryadva rivers and ended in a decisive Russian victory. From this triumph Demetrios received the surname Donskoy. In thanksgiving he established churches and monasteries; the victory is remembered as the first in which the united Russian princes broke the dominance of the Horde in open battle.
Repose and glorification
Demetrios reposed on May 19, 1389, and was buried in the cathedral of the Archangels in the Moscow Kremlin among the princes of his house.
He was glorified among the saints by the Local Council of the Russian Orthodox Church in 1988, held in the year of the millennium of the Baptism of Rus'. His wife, Saint Euphrosyne (in the world Eudokia) of Moscow, who founded the Ascension Convent in the Kremlin and is commemorated on May 17, is also numbered among the saints.