Hygeine in the Napoleonic Wars was simply horrible.   Hospitals and treatment stations were overcrowded, poorly ventilated, and filthy.  Few if any soldiers had any basic knowledge or idea of hygeine and no thought was given to sterilization.

    Surgeons would often reuse the same scalpel, saw, or set of needles patient after patient.   If they washed their hands, the bowl which they did it in would often become as dirty as the instruments involved in the surgery.  There is no question why disease was so prevalent.

    There were no effective disinfectants and the surgeon's apron served as a place on to which wipe their hands.   No wonder why germs loved it; those disgusting places were often ideal breeding grounds for various types of germs!