The Louse That Halted an Army in Russia

The disastrous effects of the Russian invasion on Napoleon Bonaparte’s army are well known. Less widely known are the reasons for the defeat of Napoleon’s Grand Army. Although Russian resistance, brutal weather and the lack of food and water decimated the French army, new genetic evidence proves that Pediculus humanus, otherwise known as body lice, had a key role in the debacle.

Years ago, researchers led by Dr. Didier Raoult unearthed 2 kg of material containing bone fragments, clothing remnants, and segments of body lice from soldiers buried in a mass grave in Vilnius, the capital of Lithuania. Analysis of the material proves that almost one-third of those buried there were affected by louse-born infections such as typhus and trench fever.

Raoult and his colleagues from the University of the Mediterranean, Marseille, France, studied segments of body lice as well as the dental pulp from soldiers’ teeth. The dental pulp revealed DNA from Bartonella quintana and Rickettsia prowazekii, the agents that cause trench fever and epidemic typhus, respectively. When the DNA of such pathogens is present in teeth, the team concluded, it is very likely that the organism was the cause of death.

Typhus fever and typhoid fever are two different entities. While typhoid fever is a water-borne disease caused by a bacillus, typhus fever derives from a class of organisms that are carried by lice and are between a large bacterium and a virus in size. Under epidemic conditions, the typhus mortality rate nears 100 percent.

In 1812, Napoleon marched into Russia with 500,000 soldiers, leading what up to then had been Europe’s largest army. By the time the French army reached Moscow, only 90,000 soldiers out of a central force of more than 300,000 remained.

Conquering Moscow proved to be a Pyrrhic victory, for most of the capital’s citizens had already abandoned the city and set fire to it. There was almost no food, no shelter, and typhus raged among the soldiers. The only option was retreat.

Until recently, it had been assumed that Russia’s brutal winter was one of the main causes of the French soldiers’ deaths. This idea had been buttressed by Napoleon’s report to the Senate on Dec. 20, 1812: “My army has had some losses, but this was due to the premature rigor of the season.” He thus tried to deflect criticism of his bad decisions during the campaign.

One decision that proved particularly costly was to continue the march toward Moscow despite tremendous loss of life during the march and his own generals’ desperate pleas to halt the invasion. Undaunted, Napoleon answered his generals: “The very danger pushes us on to Moscow. The die is cast. Victory will justify and save us.”

In December 1812, the retreating army reached Vilnius with only 7,000 soldiers and 20,000 stragglers. From there they continued their retreat, leaving the sick and wounded in Vilnius. Those who died there were buried in mass graves.

Napoleon’s Grand Army was destroyed during the invasion of Russia. Of the more than 400,000 military deaths, 220,000 can probably be attributed to typhus. A great dream had become a great nightmare.

Although historians had assumed that disease played a big part in dooming the invasion of Russia, the investigation by Raoult and his colleagues provided the first solid evidence in support of this belief. The confirmation by a team of medical researchers that typhus transmitted by lice was one of the main reasons for Napoleon’s defeat shows the value of their technique in helping to reinterpret history. That Europe’s most powerful army was defeated by a humble microbe should be cause for sobering reflection in these troubling times.

Dr. Cesar Chelala is a co-winner of the 1979 Overseas Press Club of America award for the article “Missing or Disappeared in Argentina: The Desperate Search for Thousands of Abducted Victims.”