What events caused the downfall of Napoleon?

Answer 1

You can tell throughout the last few years of Napoleonic rule the his judgement was declining; he had no real Navy, the Moscow campaign was a big failure; and he didn't think much of Wellington, which was a huge misjudgement on Napoleons part.

Answer 2

His ego is one reason for his downfall. The biggest reason was because he underestimated Russia's power and led his armies to certain death in order to try and conquer Moscow. They suffered huge casualties and had to retreat. In result, Napoleon abdicated his throne. Napoleon's goal to conquer whole world= FAIL.

Or:

It may have been that he was overly confident not because of ego but because real life experiences that favored the tactics and stratagies employed. Napoleon never lead his armies to certain death and defeat. His troops were confident of victory when he lead them.

Answer 3

The Battle of Waterloo in 1815 was the battle in which Napoleon was finally defeated.

Answer 4

The Battle of Waterloo is generally considered by most historians to be the single most important military defeat that led to Napoleon's final downfall.