History rewritten by new DNA discoveries

Science and new discoveries have the power to rewrite The catastrophic retreat of Napoleon Bonaparte's army from Russia in the winter of 1812 has long been described as one of the most dramatic pages in European military history. Severe frost, hunger and typhus were considered the main culprits for the deaths of more than 300,000 soldiers of the "Grand Army".

A new genetic study, carried out by a team of researchers at the Pasteur Institute in Paris, however, brings a more complex perspective: the French army was also decimated by paratyphoid fever and relapsing fever transmitted by lice - two infectious diseases previously undocumented in the context of the Napoleonic campaign, Reuters reports.

• Teeth of Soldiers Buried in Vilnius

Researchers analyzed DNA extracted from the teeth of 13 French soldiers buried in a mass grave discovered in 2001 in Vilnius, Lithuania - a key point on the route of the retreat from Russia. The site contains the remains of 2,000 to 3,000 soldiers, hastily buried during the chaotic retreat. "Many soldiers arrived in Vilnius exhausted, hungry and sick. They died there in considerable numbers and were buried quickly, in mass graves,” said Nicolas Rascovan, a biologist and geneticist, head of the microbial paleogenomics unit at the Pasteur Institute and lead author of the study, published in the journal Current Biology. Genetic analysis revealed that four of the 13 soldiers were infected with the bacteria that causes paratyphoid fever, and two with the bacteria responsible for relapsing fever transmitted by lice.

• Forgotten but devastating diseases

Paratyphoid fever, transmitted through contaminated water or food, causes high fever, abdominal pain, diarrhea, weakness and sometimes a rash.

Relapsing fever, in its lice-borne form, causes repeated episodes of fever and intense muscle pain. These diseases, combined with extreme cold, lack of food and poor hygiene, created the ideal conditions for a devastating epidemic among the already weakened troops. "Cold, famine and typhus have long been highlighted as the main causes of casualties, but our results show that other infectious diseases also played a major role,” Rascovan explained.

• A more complex picture of the tragedy of 1812

A previous study, conducted in 2006, had detected the DNA of bacteria that cause typhus and trench fever, but without highlighting the presence of paratyphoid or relapsing fever. The new study demonstrates that French soldiers were simultaneously affected by multiple diseases, some with different modes of transmission - evidence of the extremely poor sanitary conditions during the retreat. "Ancient DNA allows us to identify infections, which accounts based solely on symptoms cannot do. The coexistence of multiple pathogens shows how serious the medical context of the era was,” Rascovan added. The findings provide not only a clearer medical picture, but also confirmation of how paleogenomics can complement history. The analysis of ancient DNA is becoming an increasingly valuable tool for historians, capable of verifying or contradicting hypotheses that are two centuries old. "Ancient DNA allows us to directly test historical hypotheses, adding concrete evidence to traditional narratives. We can see not only what diseases existed, but also how they evolved and spread,” the French researcher emphasized. Thus, the retreat from Russia no longer appears only as a military catastrophe caused by winter, but also as a biological tragedy - a losing battle against invisible microorganisms.