Using dental pulp extracted from the teeth of soldiers who died during Napoleon’s disastrous retreat through Russia in 1812, a new study finds DNA evidence that epidemic typhus and trench fever ran rampant among the French Grand Army. The study, published in the Jan. 1 issue of The Journal of Infectious Diseases, now available online, identifies the specific species of louse-borne pathogens that were a major cause of death among the remains of the retreating army.