“From the opening shots at Fort Sumter to the annihilating fire from Little Round Top against Pickett’s men and the months of bombardment at Petersburg, artillery played a role not really seen in American experience before the Civil War,” wrote Steven A. Wilson in his essay “Heavy Artillery Transformed.” The battle of Fort Pulaski, Georgia (April 10-11, 1862) illustrates this revolution in big gun technology.
Fort Pulaski commanded the mouth of the Savannah River and approaches to the city of Savannah, a vital cotton exporting port and railroad and manufacturing center with a state arsenal and private shipyards. Union Brigadier General Thomas W. Sherman surrounded and besieged the fortress for 112 days that spring while his soldiers laboriously hauled 36 big artillery pieces of various types and sizes through the swamps to finally install them in eleven batteries on nearby Tybee Island.
To almost everyone’s surprise, the monstrous and presumably invincible citadel succumbed after only 30 hours of bombardment that blasted great gaps in the walls.
Shells flew across the now exposed courtyard and detonated near the powder magazine threatening to obliterate the fortress, its 47 guns, and 361 Confederates inside. The white flag went up. The planned 10,000-man assault would not be needed.
Just ten innovative and experimental weapons decided the outcome: two 64-pounder and two 84-pounder James rifles and five 30-pounder and one 48-pounder Parrott rifles. Confederate Colonel Charles C. Jones, Jr.: “To the new and unexpected effect of the conical shot and percussion shells ejected from the James and Parrott rifles must be credited the breaching of the wall, the partial demoralization of the work, and the accomplishment of disastrous results which speedily rendered the fortification untenable.”
Another three thousand shells and solid shot from 10 and 13-inch mortars and from 8 and 10-inch smoothbore Columbiads “admirably served by the United States troops” did comparatively little damage. “Had these guns only been employed, the probability is that structure would have preserved its integrity and would have held out for an indefinite period.”
Following the War of 1812, President James Madison ordered a new generation of coastal fortifications with greater structural durability (known as the “Third System”) to defend against foreign invasion.
Many of the 42 forts built after 1816 still exist and still display scars of the war including Fort Pulaski, Fort Sumter, Virginia’s Fort Monroe, Fort Jackson downriver from New Orleans, and Forts Morgan and Gaines in Mobile Bay.
Fort Pulaski was completed in 1847 following eighteen years of construction and nearly $1 million in costs. Second Lieutenant Robert E. Lee, a recent graduate of West Point, was assigned there as an engineer in 1829 and 1830. Wooden pilings were sunk up to 70 feet in mud. Walls were built of solid brick—an estimated 25,000,000 of them—7.5 feet thick, 25 feet high with heavy reinforcing masonry piers.
The fort was (and still is) located on Cockspur Island surrounded by wide wet marshes and broad waters of the Savannah River. U.S. Navy ships could not approach within effective cannon range and no firm ground existed on which to erect land batteries closer than Tybee Island, 1.5 miles away.
The Federal guns on Tybee Island ranged from 1,650 to 3,400 yards distant. But even the largest smoothbore cannon had little effect beyond 700 yards and no effect beyond 1,000. Expert opinion on both sides assumed long-range bombardment could only soften a target preparatory to assault. Brigadier General Joseph Totten, United States Chief of Engineers: “you might as well bombard the Rocky Mountains.”
General R. E. Lee, then commanding Confederate coastal defenses, stood on the fort’s parapet with its commander, pointed to the shore of Tybee Island and remarked: “Colonel, they will make it pretty warm for you here with shells, but they cannot breach your walls at that distance.” Lee believed the fort could not be reduced by bombardment or direct assault, only by starvation.
But military technology had experienced revolutionary innovation and sustained transformation in the last half century. In the same publication, Wilson’s fellow author, Barton C. Hacker, discusses “How Technology Shaped the Conduct of the War.”
Developments like heavy, rifled artillery, the rifle-musket, the railroad–telegraph network, and the armored, steam-powered, propeller-driven warship “were in some respects typical products of premodern patterns of technological innovation. Technology, whether civil or military, was chiefly empirical.
“Vast as the accumulation of technical knowledge had become by the mid-nineteenth century, it was still normally the product of hit-or-miss experiment by craftsmen or tinkerers, laboriously augmented over many years, unevenly developed, and slow to spread….
“Ingenuity and imagination, rather than science, dominated the efforts of both sides to devise and apply new weapons and techniques during the Civil War. Military-technological innovation still relied chiefly on lone inventors and tended to be a prolonged process.” However, beginning in the late eighteenth century, a “kind of systematic empiricism” accelerated the pace of change, growing stronger as the nineteenth century advanced.
Traditional smoothbores defined by shot size and recognizable to generations of gunners—6-pounder, 12-pounder, 24-pounder, 32-pounder—evolved to a bewildering array of smoothbore and rifled guns of various types and sizes known mostly by inventor’s names: Parrott guns, Dahlgren guns, Rodman guns, and so on.
These guns were a different breed entirely—massive rifled weapons firing explosive shells for accuracy and penetrating power. Some Parrotts shot 300-pound projectiles; other guns grew to 10, 11, or 12-inch bores. Fifteen-inch Rodmans were cast by 1863 and 20-inch Dahlgrens by the end of the war.
Inventors were experimenting here and in Europe with built-up guns and breech loaders. Powder and shell manufacture became more reliable. Processes for rifling were refined. Iron was deployed in new ways; furnace shapes were optimized, metallurgical properties investigated, and casting processes improved. Frustrating failures, burst guns, and fatalities also littered the road of progress.
In the antebellum period, Army Lt. Thomas J. Rodman proposed an improved water-cooled casting method for large-caliber Columbiads. Navy Lt. (later Rear Admiral) John Dahlgren came up with a soda-bottle-shaped gun thicker at the breech to withstand internal pressures. Rodmans became the standard for siege and coastal defense guns as Dahlgrens did for shipboard ordnance.
Robert Parker Parrott’s solution to increased chamber pressure was to heat shrink a thick wrought-iron band around the breech of a cast-iron gun, which evolved into numerous variations—the Parrott gun. On the Confederate side, John Mercer Brooke did much the same with the Brooke rifle.
Wilson: “This frothy ferment of the mid-nineteenth century represents a relatively understudied period in the history of artillery but a crucial one for understanding how traditional ordnance could be improved so that it came to be the instrument of change in the Civil War.”
Brigadier General Quincy Adams Gillmore, General Sherman’s chief engineering officer, had been studying the test records of the latest experimental Army weapons.
Gillmore suggested that rifled cannon on Tybee Island could reduce Fort Pulaski, but Sherman was concerned that conical shot would not fly true to strike point first at those distances. “All that can be done with guns is to shake the walls in a random manner.” Sherman would permit Gillmore to give it a try before the main assault.
Colonel Jones summarized the results: “Concentrating the fire of their James and Parrott guns…upon the pan coupe at the southeast angle of Pulaski, the Federals…had not only dismounted all the guns in that vicinity, but had succeeded in demoralizing, to a depth varying from two to four feet, the entire wall from the crest of the parapet to the moat.”
Despite Intense return fire from the fort, Union guns and gunners were well protected behind low-lying sand, earth, and timber breastworks. Only one Union soldier was killed and three Confederates severely wounded.
General Gillmore reported in his after-action assessment: “Good rifled guns, properly served, can breach rapidly at 1,650 yards’ distance….
“I would not hesitate to attempt a practicable breach in brick scarp at 2,000 yards’ distance with ten guns of my own selection.” Heavy round shot also could help knock down masonry thus loosened.
Department commander Major General David Hunter added his assessment: “The result of this bombardment must cause, I am convinced, a change in the construction of fortifications as radical as that foreshadowed in naval architecture by the conflict between the Monitor and Merrimac. No works of stone or brick can resist the impact of rifled artillery of heavy caliber.”
Federals occupied and repaired Fort Pulaski and controlled the South Carolina-Georgia coasts for the remainder of the war. Lee built up defenses in depth around Savannah with what forces he could muster. The city held out for two and a half years before succumbing to the encircling hosts of General W. T. Sherman, but it was strategically neutralized as a port.
This was, concluded General Gillmore, “a new era in the use of this most valuable, and comparatively unknown arm of service.”
 Steven A. Wilson, “Heavy Artillery Transformed” in Barton C. Hacker, ed., Astride Two Worlds: Technology and the American Civil War (Washington, DC, 2016), loc. 1164 of 4472, Kindle.
 Col. Charles C. Jones, Jr., “Military Lessons Inculcated on the Coast of Georgia During the Confederate War: An Address Delivered Before the Confederate Survivors’ Association, in Augusta, Georgia, April 26, 1883” (Augusta, Georgia, 1883), 7-8.
 https://www.nps.gov/fopu/learn/historyculture/battle-for-fort-pulaski.htm, accessed June 6, 2018.
 Barton C. Hacker, “How Technology Shaped the Conduct of the War” in Astride Two Worlds, loc. 322-330, Kindle.
 Wilson, “Heavy Artillery Transformed,” loc. 1211-1213, Kindle.
 T. W. Sherman indorsement to Q. A. Gillmore to Brigadier General Thomas W. Sherman, in The War of the Rebellion: A Compilation of the Official Records of the Union and Confederate Armies, 128 vols. (Washington, DC, 1880-1901), Series 1, vol. 6, 195. Hereafter cited as OR.
 Jones, Jr., “Military Lessons,” 8.
 Q. A. Gillmore to Brigadier General Egbert L. Viele, OR Series 1, vol. 6, 146-147.
 David Hunter to E. M. Stanton, April 13, 1862, OR Series 1, vol. 6, 134.
 Brig. Gen. Q. A. Gillmore, Official Report to the United States Engineer Department Of the Siege And Reduction of Fort Pulaski, Georgia, February, March, and April, 1862 (New York, 1862), 7.