This brought heavy rain across Europe that contributed to Napoleon Bonaparte's defeat. Napoleon’s artillery was among his greatest strengths, but the French emperor feared that the soggy and muddy conditions would bog down the advance of his men, horses and heavy guns. The peace treaty agreed to between France and the European powers in November 1815 reduced the size of French territory and required the defeated country to pay an enormous indemnity over the course of five years.
– Here's an unexpected theory: that Napoleon's defeat at Waterloo in June 1815 was partly caused by the eruption of an volcano in Indonesia. It's a suggestion tacked onto the end of a study by Dr. Matthew Genge of the Imperial College London published Wednesday in Geology. Titled "Electrostatic levitation of volcanic ash into the ionosphere and its abrupt effect on climate," much of the findings focus on the 1883 eruption of the Krakatau volcano in Indonesia. Genge writes that "conventional wisdom suggests" eruptions can't inject volcanic particles into the upper atmosphere "because the temperature inversion of the stratosphere acts as a barrier to convective rise"; ergo, these eruptions wouldn't have a meaningful impact on the upper atmosphere. But as Genge explains in a press release, "My research ... shows that ash can be shot into the upper atmosphere by electrical forces"—and "atmospheric electrical potential moderates cloud formation." His research into that Krakatau eruption and the average air temperature and precipitation records from the time unearthed data "consistent with a sudden effect on climate." And that takes us to Waterloo: The rainy and muddy weather is thought to have played a role in Napoleon's defeat, and Genge notes in a single paragraph that May and June 1815 are known to have been "notably wet in Europe" following the late April eruption of the Tambora volcano, which is also found in Indonesia and erupted at a greater magnitude than Krakatau. As the release notes, the findings "could confirm the suggested link between the eruption and Napoleon's defeat."