Napoleon’s Downfall due to a Volcano: Mount Tambora.

aerialVictor Hugo, referring to the Battle of Waterloo in his book Les Misérables had this to say about the weather:

Had it not rained on the night of 17th/18th June 1815, the future of Europe would have been different…an unseasonably clouded sky sufficed to bring about the collapse of a World.

During that spring of 1815 the weather was unnaturally extreme, with heavy rains and thunderstorms, which indeed may have contributed – if not determined – Napoleon’s downfall. Private John Lewis of the 95th Rifles wrote to his friends about the night of the 18th of June: ‘Rain fell so hard that the oldest soldiers never saw the like…’.

Clearly rain could not explain all, as several mistakes were made by Napoleon and by his courageous but reckless Marshal, Michel Ney, who was in command of the cavalry, even if the root of the French defeat probably lays with the poor consideration Napoleon had for British infantry. He had exclaimed that day: ‘This affair [of beating the British] is nothing more than eating breakfast!’. A costly mistake because Wellington was ahead of him in term of intelligence and knowledge of the terrain.

But putting aside tactical mistakes – such is the consensus among historians –  in spite of them Napoleon could have won the day on dry terrain. Which was then the cause of such Act of God, to use a common mercantile expression, such unnatural increase of rainfall over that short period of 3 days, which ultimately caused Napoleon’s doom?

Napoleon did not know what it was but today we suspect that the excess of rain may have been caused by a volcanic explosion in far-away Indonesia, at Mount Tambora. This possibility has been already taken into account by some historians, but then they dismissed it claiming that the effects were felt only during the following year. (1)

This is clearly wrong since a similarly powerful explosion, dating to 1453 and happening at Kuwae, 1.200 miles east of the Australian coast, had visible and powerful effects in Europe just a couple of months later. For instance St. Elmo’s fires were spotted on the copper domes of churches in Costantinople, which were interpreted as a divine sign about its impending doom. In fact the city fell  on the 23rd of May into the hands of the Turks.

The eruption of the 10 of April 1815 at Mount Tambora, on the island of Sumbawa was the most powerful in recorded history and led to a period of significant climate change and extreme weather. The column of smoke – saturated with sulphur dioxide – created by the eruption soared to 43 km into the stratosphere, thus lowering global temperatures during 1816 and causing widespread harvest failures, which later became known as the Year Without Summer.

As a result of Mount Tarabora’s series of explosions and eruptions the Earth seen from space would have looked far more brilliant than usual, as the Sun’s rays were reflected. Longitudinal winds then spread these fine particles around the globe, creating several optical phenomena, such as prolonged and brilliantly coloured sunsets and twilights which were visible even in London and Paris between June and  October 1815. The glow of the twilight sky was tinged red near the horizon and purple above. It was this natural phenomenon that created an excess of rain for 1815 followed by a strong cooling in 1816, in fact one of the coldest years ever recorded in history.

The first detonations were heard on April 5th, 1815 at Makassar on Sulawesi, 380 km away, Batavia (now Jakarta) on Java 1,260 km away, and Ternate on the Molucca Islands 1,400 km away. On the morning of the 6th of April, volcanic ash began to fall in East Java with faint detonation sounds lasting until 10 April. What was first thought to be sound of firing guns was heard on 10 April on Sumatra more than 2,600 km away.

In the early morning of the 10 April the eruptions intensified and the whole mountain was turned into a flowing mass of liquid fire. Pumice stones of up to 20 cm in diameter, like at Pompey, started to rain down around 8 pm followed by ash at 10 pm. Pyroclastic flows cascaded down the mountain to the sea on all sides of the island, wiping out the village of Tambora and causing thousand of deaths.

Napoleon Bonaparte in the morning of the 18 of June waited for the ground in front of his army to dry before ordering a frontal assault on Wellington and his allies – encirclement was out the question because of the heavy muddy terrain. It was that delay which allowed the Prussian army – he had beaten the Prussians at Ligny on the 16th – to  reach Waterloo in the late afternoon. They entered the battlefield during the most critical time of the battle, when the Duke of Wellington had already admitted defeat and issued orders for a retreat towards Bruxelles.


  1. Dennis Wheeler & Gaston Demarée The Weather of the Waterloo campaign 16 to 18 June 1815: did it change the course of history? RMeets, 2005.

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