In 1389, Dmitry Donskoy died. He appointed his son Vasily Dmitrievich as successor, with the provision that if Vasily were to die as an infant, his brother, Yury Dmitrievich, would be the successor. Vasily died in 1425 and left a child, Vasily Vasilyevich, whom he appointed as the Grand Prince (known as Vasily II). This was against the existing rule, where the oldest living brother and not a son, should have received the crown.
In 1431 Yury decided to seek the title of Prince of Moscow with the Khan of the Horde. The Khan ruled in favor of Vasily, and additionally ordered Yury to give Vasily the town of Dmitrov, which he owned. The formal pretext to start a war was found in 1433, when during the marriage feast of Vasily his mother, Sophia of Lithuania, insulted Vasily Yuryevich, the son of Yury, in public. Both sons of Yury, Vasily and Dmitry, left for Galich. They plundered Yaroslavl, ruled by an allied of Vasily II, allied with their father, collected an army, and defeated the army of Vasily II. Subsequently, Yury Dmitrievich entered Moscow, declared himself the Great Prince, and sent Vasily II to Kolomna.
Eventually, however, he did not prove himself as an efficient head of state, having alienated some Muscovites who fled to Kolomna, and even alienating his own sons. Eventually, Yury allied with Vasily II against his sons. In 1434. Vasily II's army was defeated in a major battle. Vasily Yuryevich conquered Galich, and Yury openly joined his sons. Yury became the Prince of Moscow again, but suddenly died, and his son, Vasily Yuryevich, became his successor.