A new DNA study casts doubt on the famous theory about the deaths of Napoleon's troops.

We know the story well enough: few conquerors can endure the cold of Russia. Napoleon certainly couldn't, and when in 1812 he and his legion of soldiers had to retreat from the great country due to dwindling supplies and resistance, they didn't know that the worst was yet to come.

During the Russian withdrawal, at least half of the 600,000 troops were devastated by extreme winter conditions, hunger, and disease. But now a new study has identified the specific pathogens that helped decimate the weakened forces, Science Alert reports.

While doctors of the time documented typhus (with symptoms ranging from fever to headaches to skin rashes), microbiologist Rémi Barbieri of the University of Paris Cité has found no trace of the bacteria Rickettsia prowazekii, which is responsible for the disease.

Barbieri's team extracted and analyzed ancient DNA from the teeth of 13 soldiers . They found evidence that the men had suffered from a combination of paratyphoid fever, caused by a strain of Salmonella enterica, and fever, caused by a bacterium called Borrelia recurrentis and transmitted by body lice.

"While not necessarily fatal, louse-borne fever could significantly weaken an already exhausted individual," the researchers explained in their paper. Still, Barbieri and his team caution that the fact that their analysis didn't detect typhus doesn't mean it didn't contribute to the infamous loss of soldiers, as they only sampled 13 individuals . More than 3,000 bodies lie in the mass graves found in Vilnius, Lithuania, in 2001 .

"Louse-borne fever could significantly weaken an already exhausted individual."

Other researchers have noted that several diseases match the historical account of symptoms, including typhus . Many of the men were buried in their uniforms and also with horses. The lack of weapons suggests these individuals did not die in combat, Barbieri and his team explain. " Analysis of a larger number of samples will be necessary to fully understand the spectrum of epidemic diseases that affected Napoleon's army during the Russian retreat," they write.

In light of our results, a reasonable scenario for the death of these soldiers would be a combination of fatigue, cold and various diseases , including paratyphoid fever and louse-borne relapsing fever.

We know the story well enough: few conquerors can endure the cold of Russia. Napoleon certainly couldn't, and when in 1812 he and his legion of soldiers had to retreat from the great country due to dwindling supplies and resistance, they didn't know that the worst was yet to come.