Disunion follows the Civil War as it unfolded.

On a hot summer day in 1861, Commander Matthew Fontaine Maury and his son Richard, now a junior officer in the Confederate Army, rowed from Rockett’s Wharf in Richmond, Va., toward the middle of the James River and set afloat two kegs filled with rifle powder. The kegs bobbed down river toward a buoy, where they became entangled, as intended. But nothing happened.

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Maury, however, was unwilling to admit defeat. He had his son row back toward the buoy. On his father’s command, Richard pulled the rope connected to the mine’s trigger. “Up went a column of water fifteen or twenty feet,” Richard Maury wrote years later. “Many stunned or dead fish floated around.”

The jubilant Maurys were drenched in the baptismal water of modern mine warfare in North America.

Matthew Maury, a respected engineer and the former superintendent of the National Observatory, was not the first American to successfully detonate percussion mines. The inventor David Bushnell had twice attacked anchored British warships during the Revolution, but with little success. Robert Fulton had for years tried to interest navies in Europe and the United States in his mines before and during the War of 1812. The Maurys were not even the first Americans to successfully explode electrically detonated mines, weapons not dependent on tides or currents, to sink a ship. Samuel Colt did that several times in 1844 in demonstrations in New York harbor and at the secretary of the Navy’s request in Washington.

But these early efforts came to naught. Fulton, despite his fame, attracted only limited attention among naval officers more interested in blue-water warfare. Even progressive American naval officers, like Matthew C. Perry, preferred investing in steam power and blue water warships over mines.

This time, though, was different. The Confederate government lacked a navy of almost any kind, and it had thousands of miles of coast and inland waterways to defend. As a result, it was desperate enough to commit money to torpedoes, as mines were called then. As its military leaders realized early on, torpedoes were deadly and cheap; and for a government short of bullion, they could be a military godsend.

And so, although the Confederate Navy’s top priority in 1861 remained rebuilding the scuttled frigate Merrimack as an ironclad, Secretary of the Navy Stephen Mallory requested $50,000 from the Confederate Congress for mines. Mallory also put Maury in charge of coastal defenses and detailed a few men to work out of an office at 9th and Bank Streets in Richmond to perfect the South’s secret weapon.

Maury’s task went far beyond mine technology, and within six months Mallory was being pilloried by Southern journalists and politicians for successive Confederate losses along the rivers of the Western theater, including Forts Henry and Donelson, Island No. 10 in the Mississippi and New Orleans. But Maury’s attention was elsewhere: namely, the defense of Richmond. Largely out of sight of newspapermen and congressmen, Maury was turning the James River into a Union Navy death trap.

The first layer of the city’s defense was already in place. Large guns from the naval shipyard in Portsmouth, Va. had been moved into positions at Drury’s Bluff and Chaffin’s farm, sites that commanded the river below Richmond. But Maury had bigger plans. In an 1862 report, he described three ranges of torpedoes he had placed downriver. There were 15 in all, encased in watertight casks, containing 160 pounds of explosives, electrically connected to a battery on shore and kept in place by buoys. They were connected in such a way that “each range are exploded at once,” thus capable of destroying attacking gunboats approaching in pairs or single file.

Eleven other torpedoes with 70 pounds of explosives were being put in reserve. Also in reserve at Chaffin’s farm were advanced galvanic batteries, at least one lent to Maury by Socrates Maupin, a professor of chemistry and pharmacy at the University of Virginia. Maury, as a member of the governor’s advisory council, Virginia’s de facto War Ministry after secession, had arranged with Maupin to use the university’s laboratories to test and develop better batteries, different acid combinations, improved watertight casks and stronger insulated wires to make the torpedoes more deadly. Richmond’s layered river defense, especially the mine ranges, became a model for other cities, including Wilmington, N.C., Mobile, Ala., and Charleston, S.C.

From the start, the Union Navy tried countering torpedoes with fenders and booms around large ships, as well as nets, grapnels and iron cutters to sever wires. Union ships dragged rivers all across the South, trying to break the electrical connections between batteries and torpedoes. Naval officers also asked their Army counterparts to sweep riverbanks for snipers and mine operators. Nevertheless, the deadly efficacy of torpedoes hampered Union advancement along rivers, as well as movement among blockade ships off the Southern coast. In explaining why his April 1863 attack of ironclads on Charleston had failed, Flag Officer Samuel F. DuPont blamed his ship commanders’ “fear of these ghosts,” the hidden obstructions and invisible torpedoes that filled the harbor’s channels.

While mines used to defend ports and rivers raised few ethical questions, their use on land and against nonmilitary targets troubled many Confederate leaders – especially army officers on the eastern front. In a debate that continues today, many argued that land mines were too indiscriminate to reliably kill only enemy combatants. And even then, they argued, such devices — tripped remotely, often from hiding — were a cowardly, unchivalrous method of war, unbecoming of Southern soldiers.

Nevertheless, exigency often trumped ethics, especially in the Western Theater. Gen. Leonidas Polk, a former bishop and a longtime Maury acquaintance, wrote from Columbus, Ky., “I feel constrained to urge upon you the necessity of at once furnishing me an officer familiar with the subject of submarine batteries and capable of a practicable application of this species of defense to the Mississippi River.” But Polk had further plans for the devices: Lt. Isaac Brown, one of Maury’s associates, not only mined the waters of southwestern Kentucky but also buried iron containers loaded with explosives to be detonated electrically along two routes leading into Columbus. Union soldiers discovered the torpedoes and dismantled them before they could explode.

Confederate officers soon began deploying land mines, also known as “subterra” mines, in the east as well. Brig. Gen. John Bankhead Magruder, commanding Confederate forces on the Virginia Peninsula, had witnessed how the Russians used mines during the Crimean War, knowledge he likely deepened in the late 1850s, when he was posted to Washington alongside his brother George, the chief of the Navy’s ordnance bureau. He also established a strong friendship with Maury during that time.

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Magruder, an amateur actor nicknamed “Prince John,” is now best remembered for his successful deceptions during the siege of Yorktown in April 1862. He marched and countermarched his troops and cannons along a 13-mile defensive line, thus creating the impression of a much larger force than the 33,000 men under his command.

Less well known is the fact that Magruder was the first commander to employ mines on a large scale during the American Civil War. His soldiers hid mines in the sand around Yorktown, along its streets and roads and inside houses. After Yorktown was abandoned in May 1862, various Union units reported serious injuries and a few deaths from exploding mines.

Magruder wasn’t alone in experimenting with mines. Gabriel Rains, an officer under Magruder, had even longer and more personal experience with mines than his commanding officer, having used them during the long-running Seminole Wars in Florida. A few months before the Confederate retreat from Yorktown, Rains was engaged in mining efforts in the James and the York Rivers to disrupt the Union Navy; why not, he wondered, place subterra mines leading up the peninsula from Fortress Monroe, the headquarters of the Union campaign? In the end he decided against it; too many civilians, he realized, were using the roads to flee advancing Union soldiers.

And yet a few weeks later, following a fierce skirmish at Williamsburg, Rains suppressed his earlier qualms. He had his soldiers bury four artillery shells on the main road leading to Richmond. As a lawyer watching a Union cavalry advance come to a standstill when the shells exploded on contact with the horses’ hooves noted, “They never moved a peg after hearing the report.” Years later, Rains boasted “these 4 shells checkmated the advance of 115,000 men under Gen. McClellan and turned them from their line of march.”

In response, Maj. Gen. George B. McClellan, who also had been an American observer during the Crimean War, vowed to “make the prisoners remove [the mines] at their own peril,” a threat repeated by Maj. Gen. William T. Sherman and Flag Officer David Dixon Porter.

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Early Confederate successes with land mines set off new debates on the ethics of using “weapons that wait” to maim or kill soldiers, rather than against boats or ships. Secretary of War George Randolph finally stepped in to end the increasingly heated argument between Brig. Gen. James Longstreet and Rains over using mines. Randolph, Thomas Jefferson’s grandson, drafted a series of ethical standards for mine use that may have eased some consciences in what was now becoming total war. And yet, in doing so, he helped make land mines an accepted part of the Southern arsenal.

As technology advanced and more officers employed torpedoes, new political and ethical questions surfaced. Mines, some argued, shouldn’t be restricted to the battlefield; they could hamper all aspects of the Union war effort. But how far should the Confederacy go in taking mine warfare to all matters of Northern civilian life and commerce?

What prompted the most troubling debate was the “coal torpedo,” an explosive device set in a block of cast iron “dipped in beeswax and pitch and covered with coal dust,” so that it looked like a regular piece of coal. Confederate agents were to slip it into Union coal supplies; placed unknowingly into the burner of a steam engine, it would explode. The device was developed by the Belfast-born inventor Thomas Edgeworth Courtenay, who was quickly authorized to employ up to 25 men in a secret service to cast and distribute these devices.

Randolph’s successor, James A. Seddon now had to devise new rules of engagement. He ordered “passenger vessels of citizens of the United States on the high seas and private property in the water and [on] railroads or within the territory of the United States … not to be subject of operations” using Courtenay’s devices. “But the public property of the enemy may be destroyed wherever it may be found.”

The use of mines never had a decisive impact on the war, though in one incident it came close. On Nov. 27, 1864, the Confederates found “the public property of the enemy,” a troop transport named Greyhound, steaming down the James River. Greyhound also served as Maj. Gen. Benjamin Butler’s floating command post. Aboard with Butler were his staff, a convalescing major general and Flag Officer Porter, meeting in the ship’s upper deck salon. It was, in the words of today’s war, an especially “high value target.”

Just as the ship passed the settlement of Bermuda Hundred, a few miles downriver from Richmond, there was a huge explosion in the engine room. Smoke began filling the ship, but the quick-thinking engineer “closed the throttle-valve, stopping the vessel, and opened the safety-valve,” letting the steam escape. No one was killed in the blast. Nevertheless, the explosion gave the Union officers great pause. “In devices for blowing up vessels the Confederates were far ahead of us, putting Yankee ingenuity to shame,” Porter wrote years later.

Indeed, by war’s end the Confederates had added timers to the torpedoes to better sabotage barges, transports, warehouses and armories. By then serving in Europe, Maury provided the Confederacy with the latest exploders from the Continent; he was also exchanging letters with the head of the French Marine Ministry on developing self-propelled torpedoes for use at sea.

Historians estimate that mines claimed 35 Union ships and one Confederate vessel (in his postwar memoir, Rains claimed 58). There are no accurate figures on how many soldiers and civilians were maimed or killed by subterra explosives planted on land. While ethical debates remained, as the Civil War progressed and the Union brought its numerical and industrial superiority to bear in the total-war phase of the fighting, Confederate leaders felt they had no choice but to use mines to defend countless Southern cities (the Union also used mines on occasion, most famously at the Battle of the Crater outside Petersburg).

In the end, Rains firmly believed that he had advanced the science of war. He also best captured the moral dilemma of mine warfare. “Each new invention of war has been assailed and denounced as barbarous and anti-Christian,” he wrote much later. “Yet each in its turn notwithstanding has taken its position by the universal consent of nations according to its efficiency in human slaughter.”

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Sources: Matthew Fontaine Maury Papers, Library of Congress; Official Records of the War of the Rebellion, Navy, National Archives and Records Administration; Richard L. Maury, “Brief Sketch of the Work of Matthew F. Maury”; Gregory K. Hartman with Scott Truver, “Weapons that Wait: Mine Warfare in the United States Navy”; Milton F. Perry, “Infernal Machines”; Gabriel J. Rains and Peter S. Michie (Herbert Schiller, ed.), “Confederate Torpedoes”; Raimondo Luraghi, “A History of the Confederate Navy”; Frances Leigh Williams, “Matthew Fontaine Maury: Scientist of the Sea”; Charles Lee Lewis, “Matthew Fontaine Maury: Pathfinder of the Seas”; D.D. Porter, “Incidents and Anecdotes of the Civil War”; John M. Coski, “Capital Navy: The Men, The Ships and Operations of the James River Squadron”; Paul D. Casdorph, “Prince John Magruder: His Life and Campaigns”; Warren Lee Goss, “Recollections of a Private”; “Battles and Leaders of the Civil War,” in Century, Vol. 29, Issue 5, March 1885; Richmond Daily Dispatch, July 7 and July 10, 1862; Journal of the Congress of Confederate States, Vol. 5, Aug. 28, 1862; Joseph M. and Thomas H. Thatcher, “Nasty Little Confederate Coal Bombs,” Civil War Times, December, 2011.

John Grady, a former editor of Navy Times and a retired director of communications at the Association of the United States Army, is completing a biography of Matthew Fontaine Maury. He is also a contributor to the Navy’s Civil War Sesquicentennial blog.