Answer:
the invasion of Russia
Explanation:
Though other campaigns had taken a toll on Napoleon's military, the invasion of Russia is generally considered his largest failure. In 1807, Napoleon forced Russia to sign a treaty against trading with Britain. When Russia refused to continue this treaty in 1812, France invaded. French soldiers suffered from freezing, starvation, and Russian attacks during the invasion. The Russians burned their own cities instead of allowing the French to control them, and Napoleon was forced to end the invasion.
