Final answer:
Napoleon's defeat in Russia severely weakened his army and empire, leading to his abdication, brief return to power, final defeat at Waterloo, and eventual exile to St. Helena.
Step-by-step explanation:
The defeat of Napoleon in Russia marked a significant turning point in his fortunes. Napoleon's grand army suffered immense losses, diminishing from 650,000 men to only about 100,000 upon their retreat. The Russian campaign's failure, compounded by a harsh winter, disease, and the scorched earth policy by Russia, led to a severe weakening of Napoleon's position. The coalition of European powers, sensing vulnerability, rallied and ultimately compelled Napoleon to abdicate in 1814 after the Battle of Leipzig and the invasion of France by Allied forces. Despite briefly returning to power, he was defeated at Waterloo and exiled to St. Helena, where he spent the remainder of his life.