Scientists Reveal Ancient Diseases That Plagued Napoleon’s Army

Research led by scientists at Institut Pasteur has uncovered new insights into the illnesses that devastated Napoleon Bonaparte’s army during its ill-fated campaign in Russia in 1812. By analyzing ancient DNA from the teeth of soldiers buried in a mass grave, the study identifies not only the well-documented typhus but also two additional diseases: paratyphoid fever and relapsing fever.

During the summer of 1812, Napoleon commanded an army of approximately 500,000 troops to invade Russia. The Russian forces employed scorched-earth tactics, retreating while destroying resources. By autumn, the French army found itself in a disastrous situation, with an estimated 300,000 soldiers succumbing not to enemy forces, but to a combination of illness, extreme cold, starvation, and exhaustion.

New Discoveries from Ancient DNA

Historical narratives have largely attributed the catastrophic losses to typhus, a disease transmitted by lice. However, the recent study, published in the journal Current Biology, analyzed microbial DNA fragments found in the teeth of 13 soldiers from the mass grave unearthed in Vilnius, Lithuania, in 2001. The researchers detected DNA from Salmonella enterica, which causes paratyphoid fever, and Borrelia recurrentis, responsible for relapsing fever.

Stephan Talty, an author and historian, noted the romanticized narrative surrounding typhus as a form of divine retribution against Napoleon. He commented, “Though the sample size is small, the new evidence makes a strong case that there were other infections at work.” The harsh conditions faced by the army made it plausible that multiple diseases contributed to the staggering death toll.

Excavation and Historical Context

The mass grave, containing the remains of over 3,000 soldiers, revealed dismal burial conditions. Excavations showed that corpses were hastily interred, often alongside horse skeletons, indicating a chaotic end for many. Previous research had confirmed the presence of Rickettsia prowazekii, the bacteria responsible for typhus, and Bartonella quintana, which causes trench fever.

Remi Barbieri, a postdoctoral researcher at Institut Pasteur, revisited these samples to utilize modern genomic sequencing techniques. This unbiased approach allowed researchers to identify various pathogens beyond their initial expectations. “We started like this, but we found other stuff than expected,” said Barbieri, who is now at the University of Tartu in Estonia.

Anne Stone, an anthropological geneticist at Arizona State University, praised the study for its methodological advancements. “Technically, it’s very well done – with very challenging samples because the preservation is terrible,” she remarked.

In their findings, the researchers identified Salmonella enterica in four samples, which can cause serious gastrointestinal symptoms. Additionally, some samples indicated the presence of Borrelia recurrentis. While these diseases are typically not life-threatening today, they posed a significant risk to an army already weakened by harsh conditions and inadequate supplies.

Barbieri and Rascovan emphasized that their findings do not absolve typhus of its role in the disaster but highlight the multiple health crises facing Napoleon’s troops. Historical accounts, including one from army physician J.R.L. de Kirckhoff, described severe gastrointestinal distress attributed to contaminated food, further illustrating the dire circumstances.

This latest research not only sheds light on a pivotal moment in military history but also enhances our understanding of how diseases evolve and impact human lives. As Talty aptly noted, “This new study reinforces how impossible the whole enterprise was; in a time before railroads and antibiotics, the invasion was doomed before it even began.”