DNA reveals the real killers that brought down Napoleon's army

Summary

Napoleon’s march on Moscow remains one of history’s most catastrophic military retreats. As his army withdrew, tens of thousands perished. But what killed them?There was hunger and cold, but also a mysterious illness that was long thought to be typhus.Now, more than two centuries later, DNA from the soldiers’ teeth is rewriting that history, suggesting the answer instead could be bacteria that cause enteric and relapsing fevers.“It’s very exciting to use a technology we have today, to detect and diagnose something that was buried for 200 years,” said Dr Nicolás Rascovan of the Institut Pasteur in France, who led the new study.What caused the Napoleonic defeat?In June 1812, Napoleon invaded Russia with an army of around half a million men – then the largest force ever assembled for a single campaign. By September, his troops reached Moscow without defeating the Russian army, only to find the city deserted and deliberately burned.With no decisive victory or peace proposal in sight and winter closing in, Napoleon ordered a retreat five weeks later, one that would see his army decimated by cold, hunger and disease.Historians have long debated which pathogens contributed to this catastrophe. Contemporary accounts by doctors and army officers blamed typhus – a louse-borne infection common among soldiers at the time – and the discovery of body lice plus DNA on soldiers’ remains bolstered this assumption.This shows the power of ancient DNA technology to uncover the history of infectious diseases that we wouldn't be able to reconstruct with modern samples [...] This information provides us with valuable insights to better understand and tackle infectious diseases today.- Dr Nicolás Rascovan, Institut Pasteur in FranceTo investigate whether typhus was really to blame, Rascovan and his team sequenced DNA from the teeth of 13 soldiers buried in a mass grave in Lithuania using next-generation DNA sequencing. This new technology is capable of revealing more from ancient genetic m...