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**Napoleon Bonaparte’s Catastrophic Invasion of Russia: New Discoveries Challenge Long-Held Disease Theory**
Napoleon Bonaparte’s disastrous invasion of the Russian Empire in 1812 remains one of history’s most infamous military blunders. In the summer of that year, the French emperor led over 615,000 troops of the Grand Army across Eastern Europe’s Neman River, aiming to compel Russia to join a continental blockade against the United Kingdom. However, within less than six months, more than half a million of Napoleon’s soldiers succumbed to starvation, hypothermia, and disease.
The failed campaign is still extensively studied today. Historical accounts have long suggested typhus as a leading cause of death among the French troops. Yet, recent microbial analyses of Grand Army soldiers’ remains reveal that at least two other pathogens were central in claiming thousands of lives.
A new study published in the journal *Current Biology* overturns the long-held belief that typhus was the main killer. Instead, researchers found that enteric fever (typhoid) and relapsing fever played major roles in the deadly toll.
### Why the Typhus Theory Persisted
It is understandable why typhus theory prevailed for decades. French doctors and soldiers’ primary accounts frequently cited typhus as potentially responsible for more deaths than the Russian army itself. Supporting this, the discovery of typhus’s main vector—body lice—on bodily remains, along with trace DNA of *Rickettsia prowazekii* (the bacteria causing typhus), reinforced this narrative.
### New Technologies, New Insights
Recent advances in sequencing technology prompted a team of microbial paleogenomicists led by Nicolás Rascovan from France’s Institut Pasteur to reexamine the causes of death among the Grand Army casualties. Their research focused on remains retrieved from a mass grave in Vilnius, Lithuania—a site along the French army’s retreat route in December 1812.
After DNA was extracted and sequenced from the teeth of 13 soldiers, the team filtered out environmental contamination to search specifically for bacterial pathogens. Surprisingly, none of the samples showed evidence of typhus. Instead, fragments of *Salmonella enterica* and *Borrelia recurrentis* were detected.
*Salmonella enterica* is the bacterium responsible for enteric or typhoid fever, while *Borrelia recurrentis* causes relapsing fever.
### Explaining the Overlap with Typhus
This discovery sheds light on why typhus had been misidentified for so long. Enteric fever’s name derives from its symptomatic similarities to typhus—“typhoid” literally means “resembling typhus.” Notably, enteric fever was not recognized as a distinct disease until later in the 19th century.
Relapsing fever, meanwhile, is also transmitted by body lice, the same vector linked to typhus. This overlap likely contributed to earlier confusion in identifying the exact pathogens involved.
### Reassessing Previous Findings
Rascovan’s team also revisited prior detections of *R. prowazekii* (typhus) and trench fever (*Bartonella quintana*) in the same mass grave. They suggest that earlier identifications may have been affected by different sequencing technologies—namely polymerase chain reaction (PCR).
According to Rascovan, “Ancient DNA gets highly degraded into pieces that are too small for PCR to work. Our method is able to cast a wider net and capture a greater range of DNA sources based on these very short ancient sequences.”
### An Unexpected Historical Connection
The study also revealed an intriguing historical link. The strain of *Borrelia recurrentis* found in Napoleon’s soldiers traces back to a lineage previously discovered in Iron Age Britain, approximately 2,000 years earlier.
Interestingly, all previously sequenced modern *B. recurrentis* strains belong to entirely different lineages. The one uncovered in this study appears to have survived long enough to wreak havoc on the Grand Army.
“It’s very exciting to use a technology we have today to detect and diagnose something that was buried for 200 years,” said Rascovan.
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This groundbreaking research not only challenges established historical narratives but also demonstrates the power of modern technology in uncovering hidden truths from the past.
https://www.popsci.com/science/napoleon-army-disease-cause/