The Role of Infectious Diseases in Napoleon’s 1812 Campaign

Napoleon’s campaign against Russia in 1812, known as the “Patriotic War of 1812,” witnessed one of the most disastrous retreats in history. To understand the role of diseases in this collapse, researchers from the Microbial Genomics Unit at the Pasteur Institute collaborated with the Biocultural Anthropology Laboratory at Aix-Marseille University. The team analyzed the DNA of thirteen French soldiers excavated in 2002 from a burial site in Vilnius, Lithuania, and discovered the DNA of infectious organisms using modern sequencing technology.

Discovered Diseases and Their Impact

The researchers identified two distinct pathogens: Salmonella enterica (serovar Paratyphi C), which causes paratyphoid fever, and Borrelia recurrentis, the bacteria responsible for relapsing fever. The latter is transmitted by lice and causes alternating periods of fever and recovery. Despite their differences, both can cause severe fever, fatigue, and acute digestive disorders. Their combined effect may have exacerbated the soldiers’ suffering at a time when cold, hunger, and poor sanitation were already burdensome.

Among the thirteen soldiers examined, the DNA of Salmonella enterica Paratyphi C was found in four individuals, and Borrelia recurrentis was detected in two. This represents the first direct genetic confirmation of these pathogens in Napoleon’s army.

Genetic Evidence from Napoleon’s Soldiers

Although the number of samples analyzed was small compared to the thousands of remains in Vilnius, researchers cannot yet determine the prevalence of these infections. The tested soldiers represent a small fraction—13 out of more than 3,000 bodies at the site and approximately 500,000 to 600,000 soldiers who participated in the campaign, of whom about 300,000 died during the retreat.

These findings complement previous research that identified Rickettsia prowazekii (the cause of typhus) and Bartonella quintana (responsible for trench fever), both suspected to have spread through the ranks during the retreat.

Understanding the Past to Protect the Future

Nicolas Rascovan, head of the Microbial Genomics Unit at the Pasteur Institute, stated, “Access to genetic data of pathogens that spread in historical populations helps us understand how infectious diseases evolved, spread, and disappeared over time, and identify the social or environmental contexts that played a role in these developments.”

The team worked in collaboration with scientists from the University of Tartu in Estonia to develop an innovative documentation workflow that includes several steps, including a lineage-driven interpretive approach to analyze the degraded genome fragments recovered.

Linking History and Disease

The team’s results closely match historical descriptions of the fevers that swept through Napoleon’s forces. This connection strengthens the theory that infectious diseases contributed to the catastrophic outcome of the 1812 campaign, alongside other factors such as fatigue, hunger, and the harsh Russian winter.

Ultimately, Napoleon’s 1812 campaign ended in defeat, forcing a massive retreat that decimated his army. Russian forces reclaimed Moscow, marking a turning point that dealt a fatal blow to Napoleon’s military ambitions.

Conclusion

The investigation into Napoleon’s 1812 retreat highlights the role of infectious diseases in major historical events. By using modern techniques to analyze ancient DNA, researchers have provided new insights into how diseases influenced the outcomes of wars. Understanding these events can offer valuable lessons in how to manage infectious diseases today.