Cold, Hungry and Thirsty, Napoleon’s Troops Also Suffered From Several Diseases as They Retreated From Russia

New research finds evidence of two previously undocumented infections that likely plagued the French emperor’s Grande Armée during the retreat from Moscow

Sarah Kuta | Daily Correspondent

October 28, 2025

Share

Copy linkEmailSMSFacebookXRedditLinkedInBlueskyPrint

Add as preferred source

By the time Napoleon Bonaparte’s troops limped out of Russia in 1812, they were freezing, starving and dehydrated. They were also sickened by at least two previously undocumented diseases, according to a new study published October 24 in the journal Current Biology.

French researchers say soldiers in Napoleon’s Grande Armée were likely plagued by relapsing fever and paratyphoid fever which, when coupled with their other afflictions, could have easily killed them.

Relapsing fever is caused by Borrelia recurrentis bacteria, which gets transmitted to humans via lice. The infection is often accompanied by symptoms like headache, vomiting, nausea, muscle pain and fatigue. Paratyphoid fever, meanwhile, is caused by Salmonella enterica and spreads via contaminated food and water. It can cause fever, headaches, weakness and abdominal pain.

The findings make sense, as both diseases tended to spread in places where people “were under very poor sanitary conditions or hygiene,” says study co-author Nicolás Rascovan, a microbial paleogenomicist at the Institut Pasteur, to NBC News’ Freddie Clayton. The diseases’ symptoms also align with those reported in historic accounts of the ill-fated campaign.

The scientists discovered traces of the pathogens while studying the teeth of 13 soldiers found in a mass grave near Vilnius, Lithuania. The grave, which contained around 3,000 of Napoleon’s men, was unearthed during a 2001 construction project.

“If you have DNA of the pathogen in the blood because you have an infection, that DNA can get into the tooth,” Rascovan tells NPR’s Ari Daniel. “So then it's kind of a time machine in which you can really see the blood of the individual back then.”

Researchers first decontaminated the teeth, then carefully extracted pieces of their roots. They crushed the samples into a fine powder, dissolved the bone dust and, finally, began the slow, arduous process of sequencing the ancient DNA. When they finished, they were left with a jumble of genetic material—some from soldiers themselves, some from organisms in the grave’s soil and some from the bacteria that likely contributed to their demise.

“Once we have a huge list of all the different things that have been detected, we try to find which are the species that match a human pathogen,” Rascovan tells NPR. “It's like doing a puzzle.”

A 2006 study by a different team of scientists found segments of body lice in the mass grave in Vilnius. In three of the insects, they discovered traces of Bartonella quintana, the bacteria responsible for trench fever. Those same scientists also found B. quintana in the teeth of seven men, as well as Rickettsia prowazekii, the bacteria responsible for typhus, in the teeth of three other soldiers.

The team behind the new study did not find those bacteria this time around. But, they say, that does not mean the 2006 study was wrong. Instead, they argue, their findings add new details to the downfall of Napoleon’s army. It was likely a “combination of fatigue, cold and several diseases”—including relapsing fever, paratyphoid fever, trench fever and typhus—that doomed the French emperor’s conquest, the researchers write in the paper.

“Finding four different pathogens in such a number of individuals, it really shows that there [was] a high prevalence of infectious diseases of all kinds,” Rascovan tells NBC News.

Kyle Harper, a historian at the University of Oklahoma who was not involved with the study, was impressed by the team’s work. The findings confirm what experts have long known—that most wars prior to the 20th century were “primarily medical events,” Harper tells the New York Times’ Gina Kolata. Diseases, not weapons, were the biggest threats troops faced.

“We have these paintings in the museums of soldiers in shiny armors, of Napoleon on his horse, fit young men marching into battle,” Michaela Binder, a bioarchaeologist with Novetus, an archaeology company based in Vienna, who was not involved with the research, tells NPR. “But in the end, when we look at the human remains, we see an entirely different picture. Their bones tell a story of hardship.”

Sarah Kuta | Read More

Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.