Gunpowder mines in Jackson County, Florida

by Dale Cox

Note: The following is excerpted from The History of Jackson County, Florida: The War Between the States.

Caves were a source of niter, a key component of gunpowder,
during the War Between the States or Civil War. Confederates
explored caves like this one in Jackson County to see if they
could be mined for raw materials for powder production.

Like most Floridians, the residents of Jackson County showed little initial interest in the blockade of the state’s coastline by the Union navy. Many did not think a total blockade even possible and few expected the war to last longer than a year or two. By the middle of 1862, however, it was apparent that the blockade would prove to be a factor not just for the South’s residents, but for its armies as well. Plagued with limited manufacturing capabilities when the war began, the Confederacy depended heavily on arms, ammunition, and gunpowder brought in from abroad. As the blockade tightened, these avenues of supply were constricted.


In hopes of breaking the blockade and opening key ports, the Confederate Navy pushed forward projects such as the CSS Chattahoochee. Quickly recognizing that they simply did not have the means to challenge the U.S. Navy for supremacy of the waves, however, Southern leaders also embarked on an ambitious program of industrialization. Peacetime mills, foundries, and manufacturing facilities were converted and expanded to provide war material for the Southern military. Major industrial centers grew in Columbus and Augusta, Georgia; Selma and Mobile, Alabama; Richmond, Virginia, and in other key locations across the Confederate States.

It is difficult to imagine today, but the paddlewheel steamboat
Jackson carried cargoes of cotton and other commodities
down the Chipola River from Marianna throughout the war. 

In many ways, this effort to wage war by the South foreshadowed future methods of manufacturing and supply. A converted riverboat facility in Columbus, for example, provided engines for warship construction projects throughout the Confederacy, while heavy cannon for those same vessels came from ordnance complexes in Richmond and Selma. Ironworks in Alabama and Georgia, in turn, provided the raw material used for making the guns and powder works in cities such as Augusta turned out gunpowder for both cannon and small arms.

Even Jackson County, far from the booming industrial cities of the Confederacy, contributed to this effort. Cotton from the county’s plantations and farms went up the Chattahoochee and Flint Rivers to thread and textile mills where it was converted into uniforms, tents, and bandages. Tanneries like the one at Oak Hill west of present-day Alford produced boots in large numbers for the military and other shops, large and small, manufactured everything from barrels and kegs to wagon wheels and horseshoes. The county’s forests provided heavy timbers, milled lumber and even enormous pine masts for naval construction. Beef, pork, and grain from Jackson County supported Southern armies in the field as far away as Virginia, but primarily in Tennessee and Georgia.

Gunpowder, however, was the key to continued resistance to the gathering armies of the North. While an army might move on its stomach, without powder for its muskets and cannons, it could not fight. A key ingredient of gunpowder was potassium nitrate, more commonly known during the 19th center as saltpeter.

Jackson County's caves proved too wet for use in mining
for saltpeter (potassium nitrate).

While there were several ways to collect or manufacture potassium nitrate, perhaps the easiest was to collect it from caves. In its mineral form, it was known as nitre (usually spelled niter today) and was commonly found in clear to whitish encrustations on the walls and ceilings of dry caves. It was formed by nitrates and alkali potassium leaching through the ground. Saltpeter could also be produced from the bat guano that accumulated on the floors of caves.

In an effort to find nitre for powder works such as the massive facility at Augusta, Georgia, the Confederate Nitre Bureau was established and Professor Nathan Pratt of Oglethorpe University was named Superintendent of Nitre for the District of Florida. A noted scientist of his day, Pratt was assigned the formidable task of developing sources for large quantities of nitre. Because the mineral was being successfully extracted from caves elsewhere in the South, his attention quickly turned to caverns that honeycomb much of Florida. Jackson County, of course, is home to hundreds of caves of various sizes.

While most of the many caves in the county were too small to be of much value for industrially producing nitre, it was hoped that several of the larger ones might hold potential. The Natural Bridge or Old Indian Cave at today's Florida Caverns State Park and the Arch Cave three miles northwest of Marianna were the best known of these. The massive tour cave at the state park was not discovered until the 20th century.

To investigate the potential of the caves in Jackson County and elsewhere in Florida, Pratt traveled across much of Florida between May 28 and June 27, 1862. His investigations concentrated on caves near Marianna and Gainesville, as well as on other sources for producing saltpeter in Florida.

Professor Pratt arrived in Marianna on June 8, 1862. After conferring with local military and civic leaders, he hired a buggy and rode north from town on Carter’s Mill Road to inspect the Natural Bridge Cave. He was disappointed with what he found:

…(T)he caves are all small, the largest not over 400 yards long and from 10 to 20 feet wide, with few lateral expansions or apartments. The floors are generally rocky. Earthy floors when found of large extent, generally shallow; these are kept wet by water rushing in at the mouth or by excessive dripping from the porous ceiling above, so that nitre either is not formed or if formed is subject to constant lixiviation. Deficiency of earth or excessive wetness will describe all the caves of Florida that I examined and I consider these a sample of all as they occur in the same “rottru” porous, white limestone, of the Meiocine Tertiarry.

Nitre was a key ingredient needed to manufacture black
powder, which was used in muskets of the Civil War era.

In short, the caves of Jackson County were too wet to be of much use for extracting nitre. While the results of his examinations were discouraging, Pratt did not completely rule out the possibility that small quantities of nitre could be mined in Florida. He found one cave near Gainesville that he thought might produce as much as 1,000 pounds, enough to make a considerable quantity of gunpowder, and he thought it might be worthwhile to at least make the attempt elsewhere. While he did not expect quantities produced to be sufficient to justify the construction of Confederate government mines, he did recommend that private owners open works in the caves to see what results they could achieve.

Such efforts were apparently undertaken in Jackson County. Either during his visit or shortly thereafter, Pratt named Dr. Thaddeus Hentz of Marianna as Assistant Superintendent for West Florida and placed him under the supervision of Charles H. Latrobe of Tallahassee. The brother of Dr. Charles Hentz, who practiced medicine in the county before the war, Thaddeus Hentz was a dentist and a private in Captain Robert Gamble’s Leon Light Artillery Company. He was detached from his normal military duties so he could work in Jackson County for the Nitre Bureau. Latrobe, a native of Baltimore, was the chief engineer of the Pensacola and Georgia Railroad and also a member of Gamble’s company.

The two evidently supervised at least limited attempts to mine nitre in the caves of Jackson County, most likely from the primary one at Natural Bridge. Surviving records show that Hentz approved payment to John L. McFarlin, an Apalachicola grocer, who had hired two wagon and mule teams for 25 days each to haul dirt for the Nitre Bureau in Jackson and Gadsden Counties. Some of this earth was mined from the floors of Jackson County caves, but some also came from beneath tobacco barns, stables and other plantation buildings.

The experiment, however, was short-lived and by mid-1863 significant Nitre Bureau operations in Jackson County had come to an end. Professor Pratt’s assessment of the productivity of the caves proved accurate and the county did not become a major source of potassium nitrate for the Confederate war effort.

(End of Excerpt)

The Jackson County cave experiments ended well before the Battle of Marianna, which took place on September 27, 1864. Learn more about the battle by clicking the play button to enjoy a free mini-documentary from Two Egg TV: