By Jeffrey B. Roth

The American Civil War was a conflict that sat astride two phases in military history: It began with generals on both sides employing timeworn Napoleonic-era strategies and ended with horrific trench warfare and violence against civilian populations that foreshadowed World War I. It was also a crucible in which new combat technologies were tested, among them ironclads, machine guns and submarines. And while scientists had not yet fully grasped the germ theory of disease, it was also one of the first conflicts to see chemical and biological agents tested, and even used, as weapons.

Disease was everywhere during the Civil War. By far, the biggest killer during the conflict were communicable illnesses caused by unsanitary conditions at camp and in the field. As Andrew M. Bell of the University of Virginia has documented, early in the fighting military leaders on both sides of the war began to grasp the concept of disease vectors, as weapons.

Union planners knew that among other things, the blockade against Southern ports would exacerbate the spread of disease in the South by restricting access to food, clothing and medical supplies. Malaria was still rampant across the Deep South, and quinine was in high demand before the war. “Some parts of the South experienced shortages of quinine as early as the first summer of the war, and prices climbed each year thereafter,” Bell said. “Southern civilians suffered most of all from the quinine shortage because the Confederate government requisitioned whatever little bit made it through the blockade.”

Others sought to turn disease into an offensive weapon. One Southern planner proposed shipping clothing worn by yellow fever patients to Union military units, hoping to cause an epidemic. In 1862, R.R. Barrow, a Southern farmer, suggested taking bodies of yellow fever victims, along with contaminated clothing, to New Orleans, which was occupied by Union forces. There is no evidence that either plan was put in action.

In 1863, Dr. Luke Blackburn, a Southern sympathizer and later governor of Kentucky, plotted to infect clothing with the smallpox virus and sell it to Union troops in Washington. There may have been one Union victim of the scheme, a lieutenant in the 17th Vermont named Charles W. Randall, who believed he became ill after purchasing some undergarments from a store. Later, the store was identified as a possible recipient of an infected clothing consignment.

Another approach to biological warfare was the contamination of drinking water by retreating soldiers. Maj. Gen. William T. Sherman reported that Confederate troops retreating from Vicksburg, Va., had driven animals into ponds and then shot them. In response, the Union War Department issued General Orders No. 100, on April 24, 1863, stating: “The use of poison in any manner, be it to poison wells, or food, or arms, is wholly excluded from modern warfare.”

The Civil War also saw significant use of chemical weapons, at least in an incipient form. Union forces used variants of Greek fire, essentially incendiary mixtures that were hard to extinguish and could, in some cases, float on water. “I classify Greek fire as a chemical weapon because the formulations, when ignited, released large volumes of noxious fumes, and this was considered a useful collateral effect,” said Guy R. Hasegawa, a Civil War researcher. Greek fire was used most notably during the sieges of Vicksburg, Miss., and Charleston, S.C.

Long-range artillery shells were used as the delivery system for the incendiary compounds. There were technical problems, such as the projectiles exploding too early or not at all, doing little damage. The South also developed Greek fire weapons, but how extensively they were used in the field is unclear.

Confederates had their own ideas about chemical warfare, though none were actually employed. In one case, a commando team was given chloroform for a planned raid on the Monitor ironclad, which they would use to overwhelm sleeping sailors, but the raid never took place. The South tested a shell laden with a chemical agent that would release intense noxious gases, to be fired into Union positions. The Confederates also developed another fume-producing device to be fired into tunnels. A June 4, 1861, article in The Richmond Daily Dispatch noted: “It is well known that there are some chemicals so poisonous that an atmosphere impregnated with them, makes it impossible to remain where they are by filling larges shells of extraordinary capacity with poisonous gases and throwing them very rapidly into” an enemy position (in this case Fort Pickens, a holdout Union post along the Gulf Coast).

But the most rapid innovation took place in the North. President Lincoln exhibited great interest in the development of new weapons technology. During the war, the president would often visit the Navy Yard and consult with John A. Dahlgren, head of the ordnance department of the Navy.

Yet because there was no coordinated, systematic effort to take advantage of such innovations, many ideas remained undeveloped. Nowhere was this more true than in the realm of chemical and biological weapons, where thinking got far ahead of actual doing, and the horrific implementation of things like germ warfare and chemical agents had to wait for a later, even more barbaric conflict.

Jeffrey B. Roth is an award-winning writer and regular contributor to New York Times, Reuters, and CBS as well as a number of newspapers and magazines in the U.S. and the U.K. Follow him on Twitter or visit his Facebook page.