Which historical event is associated with the term "Waterloo"?

The term "Waterloo" is most directly associated with Napoleon's final defeat, marked by the Battle of Waterloo, which took place in 1815. This battle was pivotal as it ended Napoleon Bonaparte's rule as Emperor of the French and marked the conclusion of the Napoleonic Wars. The significance of Waterloo in history is profound; it not only led to Napoleon’s exile but also reshaped European politics. As a result, the term "Waterloo" has entered common discourse as a metaphor for a decisive defeat or failure, further emphasizing its historical importance regarding Napoleon's downfall.

The other choices do not appropriately connect to the term "Waterloo." It is not a naval battle, nor does it signify a founding moment for democracy or the start of World War I, which indicates that those events are unrelated to the meaning and implications surrounding Waterloo.