Which battle was Napoleans final downfall

The Battle of Waterloo.

Explanation:

Napoleon Bonaparte is one of the most iconic figures in the French history. He is recognized as an excellent military tactician but also as a great reformer of the country. The people were very fond of Napoleon and fully supported him in his decisions, as unlike the other rulers he actually kept his promises and cared for all people in the country not just the aristocracy.

While the reforms were all good, the bad part was that Napoleon engaged in war with the majority of Europe. While he had big success at first and moved France's borders in all directions, eventually that started to crumble as France was not able to fight on its own against everyone. One by one Napoleon started to have defeats like in Russia and Spain, but the defeat that marked the end of his reign was the at the Battle of Waterloo when he fought against an allied army and suffered great loss.