Napoleon's army was weakened by fever, new DNA testing confirms

When Napoleon ordered his army to retreat from Russia in October 1812, disaster ensued. Starving, cold, exhausted and sick, an estimated 300,000 troops died.

- Nicola Davis Science correspondent

Now researchers say they have identified two unexpected diseases among soldiers who died in the retreat - paratyphoid fever and relapsing fever - providing fresh insights into their plight.

"I think that the key thing of why [the retreat] was such a failure was the cold and the hunger. With or without infectious diseases, they would have died anyway," said Nicolás Rascovan, head of the microbial paleogenomics unit at the Institut Pasteur and an author of the study. “But I think what this [does] change is some of our knowledge of all the infectious diseases.”

Writing in the journal Current Biology, Rascovan and his colleagues describe how previous analyses of DNA from soldiers buried in the same mass grave in Vilnius, Lithuania, had revealed evidence of typhus and trench fever.