Union troops used searchlights to turn night into day and overcome the Rebel defenders of Charleston’s Battery Wagner.
Wars have a way of advancing technology much more rapidly than during peacetime, and the Civil War was no exception. Railroads, submarines, the telegraph, repeating weapons and even the canning of food were just a few of the devices and industries to benefit dramatically from research and development during the four-year conflict.
Just because the technology is available, however, doesn’t always mean it will be used effectively. Professor Robert Grant’s calcium light is a perfect example. The professor’s blinding spotlight showed great potential in the summer of 1863, during the brutal fighting for Battery Wagner, near Charleston, S.C., but its brilliant beams could have had an even greater impact for the Union cause if the U.S. Navy had been quicker to adopt the new device and if it had been used in other theaters of war.
Calcium lights had been around since the early 19th century. In 1801 University of Pennsylvania chemistry professor Robert Hare invented the oxyhydrogen blowpipe, which burned pure oxygen and hydrogen to produce an extremely intense heat. When the gases were applied to quicklime, calcium oxide, it produced a light 150 times brighter than a candle. In following years, European inventors and scientists refined the process. And by the 1840s, Robert Grant of Maine—scientist, photographer, newspaperman, promoter and entrepreneur—was using the lamp, as a projectionist, to illustrate Englishman Dionysius Lardner’s popular traveling science lectures.
In the decade and a half before the Civil War, Grant marketed his lamp with mixed success. Various railroads adopted it, and it was used occasionally on steamships. Officials in New York City, however, refused to switch their streetlamps over to calcium lights, and though Grant received a $5,000 government appropriation to develop the device for lighthouses, technical problems prevented the technology from ever being adopted. In January 1861, as secession loomed, Grant was using his invention to illuminate ice-skating ponds in New York’s Central Park. But then came the war.
After the Confederate capture of Fort Sumter in April 1861, Grant envisioned a new opportunity to capitalize on his decades of toil, although he was destined for further frustration. He hoped to install his light in Fortress Monroe, at the tip of Virginia’s Peninsula, so Union Maj. Gen. Benjamin Butler’s garrison there could keep an eye on Rebel shipping during the night. That project failed, however, because the trials of Professor Grant’s calcium light were, according to The New York Times, “a little twisted up with red tape.”
Undaunted, and backed by such notables as Maj. Gen. George B. McClellan, Grant returned to New York City to form the Calcium Light Sharpshooters, a unit created especially for night action. The original plan was for the Sharpshooters to use calcium lights to reveal and target enemy positions and movements in the dark. The federal government eventually decided it needed a more conventional troop allotment and incorporated the unit into the 102nd New York as Company E. Grant’s struggle to find acceptance and application for his light continued for two more years; his luck finally changed in the summer of 1863, thanks to continued Union frustration in conquering the port of Charleston.
By 1863 the Confederacy had transformed Charleston into one of the most heavily fortified harbors in the world. The harbor entrance was defended by a string of forts running south to north: Batteries Wagner and Gregg on Morris Island, Fort Sumter in the middle of the harbor, and Fort Moultrie on Sullivan’s Island. Behind those defenses were harbor obstructions (pilings, ropes and torpedoes), additional forts and two ironclads (with a third nearly completed)—all commanded by General P.G.T. Beauregard. To enter the harbor, Union forces would have to clear the obstructions, which first required the capture of Fort Sumter.
On April 7, 1863, the mighty USS New Ironsides and eight monitors, the pride of the Federal Navy, armed with massive 15-inch Dahlgren cannons that could hurl 440-pound shells, attempted to silence Fort Sumter. That effort failed, however, destroying the reputation of Union Rear Adm. Samuel du Pont. He was succeeded by Rear Adm. John Dahlgren on July 4.
The Federal Army was also working to conquer Charleston. In July Maj. Gen. Quincy Adams Gillmore landed 10,000 men on Morris Island as part of a plan to take Battery Wagner and then Sumter. But after a series of failed assaults, Gillmore had little choice but to settle into a siege.
Battery Wagner stretched 800 feet across Morris Island, and was defended by some 700 to 1,000 men as well as 16 large guns—three facing the sea, the others pointed inland. With the Atlantic Ocean to the east and Vincent’s Creek and marshes to the west, Union attackers had to move directly north over the narrow beach, confronted with mine – fields, a moat, palisades, 16-foot-high walls, cannons and muskets. Beneath Wagner’s sea wall and 10 feet of sand was a 30-by-100-foot bombproof that could protect the entire garrison from even the largest Union shells.
The main ship channel, meanwhile, was defended by Battery Gregg— three-quarters of a mile north of Wagner at Cummings Point—and its seven guns. The Confederates had about 1,800 men on Morris Island, and the security of Charleston depended on this outnumbered force being able to hold on to Wagner until new defensive lines could be prepared.
Gillmore, a skilled engineer, dragged 38 huge siege guns across the island in an effort to demolish the Confederate strongholds. In 57 days of firing, Federal guns hurled 24,000 missiles weighing 1,600 tons, but Wagner’s sandy walls simply absorbed the massive shells. It eventually became clear that troops would have to storm Wagner, so Federal engineers began building trenches that zigzagged across the beach toward the fort.
Most of the grueling work was done at night. During the day, the powerful Federal artillery sent the Confederates into their bombproofs. But at night, when the accuracy of those big guns was unreliable, Southern soldiers and slaves came out, filled holes, sniped at the Union details and ran reinforcements and supplies across Charleston Harbor to Cummings Point. For all the metal thrown their way, the Rebels suffered few casualties during the siege— 350 killed and wounded, or one man for every 4 to 5 tons of iron. Federal losses were about 250 men, but as the sap lines neared Wagner, progress was measured in a few feet per night
With the Federals bogged down before Wagner, General Gillmore decided he needed, literally, to put the Rebels into the limelight. At the beginning of August, Gillmore informed Dahlgren he had requested that Grant bring his calcium lights to help disrupt the Confederate supply runs to Morris Island. The lights would illuminate “Cumming’s [sic] Point, so that my batteries and your boats can see it distinctly and be themselves in deep darkness.”
Grant quickly reached South Carolina and established a base of operations. Twenty soldiers and a dozen former slaves went to work in his laboratory to produce the hydrogen and oxygen needed to fuel the oxyhydrogen blowpipes. The fuel was placed in large 250-cubic-foot cylinders, 15 inches in diameter and 8 feet long.
On August 10 Gillmore’s chief engineer, Edward W. Serrell, helped Grant install a calcium light near the guns in the center of Battery Wagner. Serrell “found that the illumination was sufficient to be serviceable in siege operations,” but Gillmore was not so pleased. He believed that by throwing a cone of light upon the water approaches and stationing guard boats in the darkness, he could break Wagner’s supply line. “An attempt to illuminate the waters near Cumming’s Point…was but partially successful,” he wrote, “as the distance—over 3,000 yards—was too great for the apparatus which we had.”
Gillmore, though, had actually underestimated the impact of the new light on Confederate operations. Rebel General Roswell S. Ripley noted on the 10th that “the fire of the enemy interfered seriously with the relief of the troops on Morris Island, he having erected a large Drummond light in a position to brightly illuminate the landing. The steamers engaged in the transfer were withdrawn and the relief discontinued for the night.”
The Confederates, who hated the spotlight, responded to the new threat with vigor. A Federal officer noted that after “Dr. Grant undertook…to light up Cumming’s Point with two calcium lights…at about 2 o’clock on the morning of the 11th, [the Confederates]…opened a heavy fire of grape, canister, and shell, which, with the fire of the James Island batteries and Sumter, stopped our working parties entirely for the first time in the siege.…This is the most spiteful fire delivered landward by Wagner since the 18th July.”
Despite that, Confederate supply runs became treacherous. As General Beauregard reported, “At times…the enemy illuminated the landing with a powerful calcium light, so as to prevent the approach of our steamers, forcing us to transport our supplies of men and munitions by means of small boats.” Confederate Major Motte Pringle’s August 30 supply run ended in disaster. Pringle was able to deliver the troops and supplies and load the men being relieved without “molestation.” But he noted that “the night had changed into an exceedingly bright one, and at the upper end of the island there was a powerful calcium light.” On the return trip, nervous Confederates at Fort Moultrie mistakenly fired on and sank Pringle’s steamer, killing two men and wounding several others. Pinned down in daylight by Union fire and at night by the calcium lights, the Confederates were increasingly unable to resupply or repair Wagner and prevent the advance of the Union sappers.
Unfortunately for the Federals, marginal relations between Dahlgren and Gillmore prevented cooperative use of Grant’s light. On July 30, Dahlgren wrote to Secretary of the Navy Gideon Welles: “There are many little things that would aid me here. For instance, the electric light which Professor Way exhibited here, and which Professor Henry knows of; it would either illuminate at night, if needed, or would serve to signal.”
“Professor Henry” was Joseph Henry, a scientist and prewar friend of Dahlgren’s, who served on a three-member Permanent Commission to review technologies for the Navy and Army. In August Henry began testing lights, as he later claimed, “to prevent the falling of the matter into the hands of charlatans.” Henry considered Grant a “quack,” and favored Professor John Thomas Way’s electromechanical mercury lamp, which rivaled calcium lights in brightness but did not require the use of explosive oxygen and hydrogen fuels. After weeks of work, however, the Navy refused to reimburse Henry for his efforts, and he canceled his tests. Dahlgren would not get the mercury lamps, and perhaps out of spite he did not mount calcium lights on his ships.
By September 5, the Federal lines had reached Wagner’s moat, and Gillmore prepared for the final assault—advancing men and guns and preparing, as he recorded, “powerful calcium lights, to aid the night work of our cannoneers and sharpshooters, and blind those of the enemy.” For the next 42 hours, Federal forces barraged the fort day and night. With the calcium lights blazing, there was little difference between the two in brightness. Gillmore reported: “The calcium lights turned night into day, throwing our own men into impenetrable obscurity, while they brilliantly illuminated every object in front and brought the minutest detail of the fort in sharp relief. In a short time the fort became silent, exhibiting but little sign of life.”
On the morning of September 6, Confederate General Ripley recorded that as Union cannons blasted the forts and the “calcium light threw its bright, silvery rays upon [Wagner’s] front,” the Federals tried to attack Battery Gregg by boat. The attack failed, however, in no small part because of poor Army–Navy cooperation.
Also on the 6th, Beauregard dispatched his chief engineer, Colonel David B. Harris, to inspect the battery. Harris recommended evacuation, writing: “The covering to the bomb-proof and magazine…need repair. We have been thus far able not only to repair damages at night, but to add from day to day to the strength of the battery; but now that the enemy’s sap is in such close proximity to the battery, and he has contrived to throw a calcium light upon the parapets at night, it is impossible to do so without a heavy loss of men. In the efforts last night to repair damages, the commanding officer of the fort reports a loss in killed and wounded of 60 to 80 men of the working party alone.”
The Federals bombarded Wagner throughout the day on September 6. As night fell, Lt. Col. Orrin L. Mann, who had recently assumed command of the 39th Illinois, spent the early evening verifying details for his posts, checking ammunition and “directing the calcium lights so that they would best reflect upon the enemy’s works….The old fort that fronted us, usually dark and frowning at night, glowed with light, revealing to the anxious eye of the sharpshooters the first appearance of rebel sentinels, who only raised their devoted heads above the parapets to fall victims to loyal lead.” Mann went on to say, “Permit me in this connection to express the opinion that the light is the most valuable auxiliary to the picket duty and siege operations.”
About 9 p.m., while Federal cannons bombarded Battery Wagner under the glare of the calcium lights, the Confederates began to pull their men off Morris Island. “The journey to Cummins Point was a perilous trip,” recalled Rebel John G. Pressley. “Shells were falling and bursting all around and over us. We kept in the shadow cast by the fort, which extended nearly to Cummins Point. The calcium light of the enemy lighted up the fort as brilliantly as on the previous night.”
Despite the evacuation, it was not until after 1 a.m. on the 7th, after a Confederate deserter came into the Union lines, that the Federals entered Wagner—too late to attack the garrison as it fled. Dahlgren’s failure to mount a light on one of his ships and illuminate the land between Wagner and Cummings Point allowed the Confederates to slip away under the dark shadow of Wagner.
Frustrated by their failure to capture the Confederates, and hoping that Sumter could now be stormed, Union Army and Navy forces separately planned and executed attacks on the night of September 8-9. Each service committed 500 men to attack the fort. The Navy reached Sumter first, and once the firing started, the Army abandoned its assault. Because of a flawed and poorly executed plan, the Federals were beaten back by only 70 defenders—in part because they failed to use calcium lights to blind the defenders. Of 500 Marines who participated in the assault, six were killed, 15 wounded and 106 captured.
By the end of September, even with the fall of Battery Wagner, the Federals had lost 2,318 men and were no closer to taking Charleston than they had been at the beginning of the year. They resorted to another siege. On September 18, the light was moved to Battery Gregg to illuminate the rubble of Fort Sumter. Inside Sumter, Rebel Major John Johnson recalled, “the first night the light was displayed…I read by it the largest type of newspaper. Our sentinels on the wall were dazzled and annoyed by it. The darkness of the night and the waters around the fort was seemingly increased ten fold by the contrast. The appearance of this light, thrown upon the battered walls and arches of Fort Sumter, was always striking and beautiful.”
For the next several months the calcium light continued to shine in the harbor, and shells rained down upon Sumter as the Federals tried to keep its defenders from repairing damage, preparing obstructions and resupplying the fort’s garrison. Sumter, and Charleston itself, would somehow hold out until almost the end of the war.
By September 1864, Grant was back in New York City, operating his lights at rallies for Democratic presidential candidate George B. McClellan. To save time, Grant premixed the fuels. But when one of his blowpipes jammed against the calcium, causing the mineral to explode, one woman was killed and another fatally wounded. The accident forever cast a cloud over Grant’s efforts.
After the war, calcium light development continued, although Robert Grant—who died in 1869—apparently never benefited from his invention. Their best application turned out to be in theatrical settings, where they were used for magic lantern shows as well as stage lighting. Their widespread utility led to that familiar show-biz expression “in the limelight”—a place the Confederates wished they had never been.
Keith Miller writes from Ridgefield, Conn. Additional reading: Trial by Fire: Science, Technology and the Civil War, by Charles D. Ross; and Sinews of War: How Technology, Industry and Transportation Won the Civil War, by Benjamin Bacon.
Originally published in the February 2009 issue of Civil War Times. To subscribe, click here.