In June, 1444, the Tartars, having taken some offense, again invaded Russia.  Vassali had no force of character to resist them.  Under his weak reign the grand principality had lost all its vigor.  The Tartars surprised the Russian army near Moscow, and overwhelming them with numbers, two to one, trampled them beneath their horses.  Vassali fought fiercely, as sometimes even the most timid will fight when hedged in by despair.  An arrow pierced his hand; a saber stroke cut off several of his fingers; a javelin pierced his shoulder; thirteen wounds covered his head and breast, when by the blow of a battle-ax he was struck to the ground and taken prisoner.  The Tartars, elated with their signal victory, and fearful that all Russia might rise for the rescue of its prince, retreated rapidly, carrying with them their captive and immense booty.  As they retired they plundered and burned every city and village on their way.  After a captivity of three months the prince was released, upon paying a moderate ransom, and returned to Moscow.

Still new sorrows awaited the prince.  He was doomed to experience that, even in this world, Providence often rewards a man according to his deeds.  The brothers of the prince, whose eyes Vassali had caused to be plucked out, formed a conspiracy against him; and they were encouraged in this conspiracy by the detestation with which the grand prince was now generally regarded.

During the night of the 12th of February, 1446, the conspirators entered the Kremlin.  Vassali, who attempted to compensate for his neglect of true religion by punctilious and ostentatious observance of ecclesiastical rites, was in the church of the Trinity attending a midnight mass.  Silently the conspirators surrounded the church with their troops.  Vassali was prostrate upon the tomb of a Russian saint, apparently absorbed in devotion.  Soon the alarm was given, and the prince, in a paroxysm of terror, threw himself upon his knees, and for once, at least, in his life, prayed with sincerity and fervor.  His pathetic cries to God for help caused many of the nobles around him to weep.  The prince was immediately seized, no opposition being offered, and was confined in one of the palaces of Moscow.  Four nights after his capture, some agents of the conspirators entered his apartment and tore out his eyes, as he had torn out the eyes of his cousin.  He was then sent, with his wife, to a castle in a distant city, and his children were immured in a convent.  Dmitri Chemyaka, the prime mover of this conspiracy, now assumed the reins of government.  Gradually the grand principality had lost its power over the other principalities of the empire, and Russia was again, virtually, a conglomeration of independent states.

Public opinion now turned so sternly against Chemyaka, and such bitter murmurs rose around his throne for the cruelty he had practiced upon Vassali, that he felt constrained to liberate the prince, and to assign him a residence of splendor upon the shores of lake Kouben.  Chemyaka, thus constrained to set the body of his captive free, wished to enchain his soul by the most solemn oaths.  With all his court he visited Vassali.  The blinded prince, with characteristic duplicity, expressed heartfelt penitence in view of his past course, and took the most solemn oaths never to attempt to disturb the reign of his conqueror.