They voided excrement about the fields perniciously

From 1776 by David McCulough. Page 30.

There had been sickness aplenty from the start, deadly “camp fever,” which grew worse as summer went on. Anxious mothers and wives from the surrounding towns and countryside came to nurse the sick and dying. “Your brother Elihu lies very dangerously sick with a dysentery…his life is despaired of,” wrote Abigail Adams from nearby Braintree to her husband John in Philadelphia. “Your mother is with him in great anguish.” Captain Elihu Adams, a farmer with a wife and three children, was one of several hundred who died of illness.

“Camp fever” or “putrid fever” were terms used for the highly infectious, deadly scourges of dysentery, typhus, and typhoid fever, the causes of which were unknown or only partially understood. Dysentery had been the curse of armies since ancient times, as recorded by Herodotus. Typhus, characterized by high fever, severe headaches, and delirium, was carried by lice and fleas, which were a plague amid the army. (One soldier recorded seeing a dead body so covered with lice that it was thought the lice alone had killed the man.) Typhoid fever, also characterized by a raging fever, red rash, vomiting, diarrhea, and excruciating abdominal pain, was caused by the bacillus Salmonella typhosa in contaminated food or water, usually the result of too little separation between sewage and drinking water.

And it was not the troops alone who suffered from camp fever. Many of those who came to nurse them were sickened, or carried the disease home, and thus it lay waste to one New England town after another. Of the parishioners of a single church in Danbury, Connecticut, more than a hundred would die of camp fever by November.

“Infectious filth” was understood to be the killer. Cleanliness in person, clean cooking utensils, clean water and unspoiled meat and produce were seen as essential to the prolonged health of the army, and this was among the chief reasons for constant insistence on discipline and order, and especially with so many thousands encamped in such close company.

As it was, open latrines were the worst of it, but there was also, as recorded in one orderly book, a “great neglect of people repairing to the necessaries.” Instead, they voided “excrement about the fields perniciously.” The smell of many camps was vile in the extreme.