Final answer:
Napoleon's Empire collapsed due to strategic blunders like the disastrous Russian campaign, failure of the Continental System, mismanagement of conquered states, and military defeats like the Battle of Leipzig which eroded his power and influence.
Step-by-step explanation:
The fall of Napoleon's Empire was largely due to a series of strategic errors and overreaches on his part. Napoleon's invasion of Russia in 1812 proved to be a major turning point, with the grueling retreat from Moscow during a brutal winter reducing his Grande Armée from over 600,000 to about 100,000 survivors. This event shattered his image as an invincible military leader. Similarly, the Continental System intended to economically isolate Britain failed as British smuggling undermined the blockade and continued to enrich the UK. Further, Napoleon's megalomaniac tendencies such as appointing his relatives to run puppet states, and ignoring the sentiments of the people he conquered only fueled growing nationalism and dissent against his rule. Finally, the Battle of Leipzig, also known as the Battle of Nations in 1813, saw a decisive defeat for Napoleon against a larger coalition force, further weakening his position and contributing to his downfall.