DNA analysis reveals what really killed Napoleon’s army in 1812

At least 300,000 men died during Napoleon’s retreat from Russia – now the latest genetic techniques have identified two pathogens that may have contributed to some of the deaths

By James Woodford

1 August 2025

The Retreat of Napoleon’s Army from Russia in 1812 by Ary Scheffer

IanDagnall Computing / Alamy Stock Photo

When Napoleon’s half-million-strong army retreated from Russia in 1812, around half the men were wiped out by disease, starvation and the extreme cold. Now, state-of-the-art DNA analysis has revealed which pathogens contributed to the catastrophe.

In the summer of 1812, Napoleon gathered as many as 600,000 troops for his invasion of Russia. However, the Tsar’s forces had abandoned Moscow and emptied the city of supplies, forcing Napoleon to retreat to the Polish border for the winter. Between October and December 1812, at least 300,000 French soldiers perished from starvation, cold and disease.

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Historical reports from survivors suggested that typhus and trench fever were the main causes of death and illness among the troops, and this was backed up by genetic testing nearly two decades ago.

Now Nicolás Rascovan at the Pasteur Institute in Paris and his colleagues have examined DNA from the teeth of 13 of the soldiers buried in Vilnius, Lithuania, where many soldiers died during the retreat, and found no evidence of either typhus or trench fever.

Instead, the team confirmed the presence of Salmonella enterica, which causes paratyphoid fever, and Borrelia recurrentis, which is transmitted by body lice and causes relapsing fever.