At one o’clock on the afternoon of July 3, 1863, a single Confederate cannon fired from Seminary Ridge. Another followed, and then the sky over southern Pennsylvania opened. In the largest artillery bombardment ever unleashed on the North American continent, 163 Confederate guns opened fire across a two-mile front, directing everything they had at the Union positions on Cemetery Ridge. The sound reached Philadelphia, sixty miles away.
Men who survived it reached for the same words in their letters and memoirs: thunder, earthquake, the end of the world. Frank Haskell, a Union officer on Cemetery Ridge who somehow lived to write one of the most vivid first-hand accounts of the battle, said the air was “all iron. ” He meant it literally: for a man standing in that field, there was no separation left between the atmosphere and the ordnance passing through it. The soldiers crouching behind the stone walls and in the rifle pits on Cemetery Ridge had already spent two days at Gettysburg.
They had watched artillery tear apart the Union First and Eleventh Corps on July 1, when Confederate guns on Oak Hill swept the fields north and west of town. They had watched it again on July 2, when a Confederate bombardment shattered the Peach Orchard salient and reduced a full Union corps to wreckage in a matter of hours. They had seen what the guns did to men at close range, when cannons switched from solid shot and shell to canister, a tin cylinder packed with iron balls that turned an artillery piece into something like an enormous shotgun. They knew what they were hearing when those 163 guns opened on July 3.
They pressed themselves into the earth and waited. The artillery of 1863 was not the smoothbore cannon of the Napoleonic era, though plenty of smoothbores remained in service. The Civil War had introduced rifled artillery on a large scale, guns whose spiraling grooves spun the projectile in flight and dramatically increased accuracy and range. A smoothbore Napoleon twelve-pounder, the standard piece of both armies, was effective to about a thousand yards with solid shot.
A three-inch ordnance rifle could reach fifteen hundred yards accurately and push an explosive shell out to nearly twice that distance. Range transformed the tactical role of artillery: guns could now engage enemy positions well before infantry could bring musket fire to bear on the crews. Range alone did not capture what artillery did to human beings. Solid shot, a cast-iron ball that did not explode, could pass through multiple men in a column before its energy gave out.
At medium range its flat trajectory made it skip across the ground, bouncing unpredictably at the height of a man’s torso. Shell, a hollow iron ball filled with black powder and fitted with a time fuse, burst into fragments that sprayed outward in every direction. Fusing technology was imperfect, and shells often burst too early, too late, or not at all, but when one burst at the right moment it produced casualties across a wide area in a way no rifle ball could match. Canister, packed with iron balls roughly the size of billiard balls, spread outward from the muzzle in a cone.
At three hundred yards a single round could sweep the front of an advancing infantry company. At close range, two or three rounds of double canister fired in rapid succession could stop an assault entirely, provided the gun crews held their nerve long enough to fire at ranges where they could see individual faces. By late on July 2, some Union batteries at the Peach Orchard were firing canister at under a hundred yards. The ground at Gettysburg added a layer of complexity.
The rolling Pennsylvania farmland was broken by ridges, hills, creek beds, woodlots, and orchards that created dead ground where artillery could not reach and elevated positions where guns at the right angle could sweep terrain otherwise protected. Cemetery Hill, Little Round Top, and Seminary Ridge were not simply names on a map. They were artillery platforms, and much of the battle was a contest over which army could place its guns on the best available ground faster than the other could respond. The average artillery crew numbered seven men per gun.
In extended action the work was brutal: ramming the powder charge and projectile down the barrel, adjusting the elevation screw, stepping clear of the recoil, repeating every thirty to forty-five seconds under optimal conditions. As crews fell, drivers and support personnel moved forward to replace them. By the afternoon of July 2, some Union batteries had replaced nearly their entire crew once over. The fighting on July 1 established how central artillery would be to everything that followed.
Confederate guns on Oak Hill opened an enfilading fire on the Union First Corps line along McPherson’s Ridge, firing along the length of the formation rather than into its front. The effect maximized the damage each projectile could inflict, because the ball traveled parallel to the line rather than striking it head-on. Regiments that might have absorbed frontal infantry pressure found themselves taking fire from an angle their cover was never designed to address. The Union line cracked during the afternoon.
The Union artillery at Cemetery Hill then did what artillery does best in desperate circumstances: it held ground that infantry alone could not have held. When both corps collapsed and retreated through the streets of Gettysburg, the guns on Cemetery Hill provided covering fire that prevented the retreat from becoming a rout. Confederate forces pursuing through town ran into those guns and stopped. Jubal Early, whose division came closest to seizing the hill that evening, pulled his men back in part because the artillery position made an assault prohibitively dangerous without infantry support.
The Union Army survived July 1 with enough organizational coherence to hold the high ground because artillery had bought time nothing else could have bought. General George Meade arrived in the early hours of July 2 and spent time riding the Union position with his chief of artillery, Brigadier General Henry Hunt. They were conducting an artillery survey, identifying where guns could be placed for overlapping fields of fire and where batteries could cover approaches the terrain made difficult for infantry to defend. Hunt was one of the most technically accomplished artillery officers in either army.
The Union fishhook line running from Culp’s Hill through Cemetery Ridge to Little Round Top was organized with artillery positioning as a primary consideration. The guns shaped the defensive line as much as the infantry did. The ammunition situation on both sides was already a concern. The armies had expended significant quantities of artillery ammunition on July 1, and the supply wagons were subject to the same road congestion that affected everything else.
Confederate artillery operated at the end of a longer and less reliable supply chain than the Union guns, a factor that would become critical by July 3. Every round fired on July 1 was a round not available on July 3. July 2 demonstrated both the potential and the limits of the Union positioning. Major General Daniel Sickles, commanding the Third Corps, moved his men forward from Cemetery Ridge without authorization, occupying a salient that extended his line to the Peach Orchard, a position he judged better for artillery.
The salient was a tactical problem from the moment it was established: it extended the line beyond supporting distance on either flank, created an exposed angle at the Peach Orchard that Confederate guns could engage from multiple directions, and advanced into ground the Confederates were already prepared to sweep. When Confederate artillery opened on the position in the late afternoon, the fire came from the west, from higher ground to the south, and eventually from guns advancing with the infantry assault. The salient became a funnel. Battery after Union battery was shattered, horses killed in their traces, men cut down at the guns.
The corps that had gone forward in good order came back in fragments. The fighting on Little Round Top produced one of the most remarkable artillery episodes of the battle. Captain Carroll Hazlett moved his battery of ten-pound Parrott rifles to the summit of that rocky hill, manhandling the pieces up the north face with ropes and the physical effort of every man in the battery, plus infantrymen pressed into service. He understood that he could not fully depress his barrels to sweep the slopes directly below.
He put the guns there regardless. His reasoning was psychological rather than technical, and it was correct. To the Union infantry fighting below, the sound of their own artillery firing from the summit communicated that the position above was held. To the Confederate infantry assaulting the slopes, guns overhead meant that any foothold gained still faced artillery from above.
Hazlett was killed by a sniper’s bullet while leaning down to hear the final words of the mortally wounded General Weed. He died at guns he had carried up an almost impossible slope, knowing they could not do everything artillery was supposed to do. Captain Freeman McGilvery’s management of the Union artillery line late on July 2 may have been the most consequential individual action of the second day. When the Third Corps salient collapsed and Confederate infantry swept toward Cemetery Ridge, a gap of roughly four hundred yards opened between the retreating Union remnants and the nearest intact infantry.
McGilvery gathered every available artillery piece he could reach from multiple commands, stretched them across that open ground, and opened fire with no infantry support on either flank. There were not enough guns to close the gap by conventional standards, but there were enough guns firing fast enough to make those four hundred yards impossible to cross in good order. He held that improvised line long enough for Union infantry to be shifted from other sectors to fill the breach. If Confederate forces had gotten through unchallenged, they would have reached Cemetery Ridge.
The cumulative cost of July 2 was severe to both artillery establishments. Union batteries had been partially destroyed and then refitted with guns and personnel from the artillery reserve, which Hunt had positioned for exactly that kind of rapid reconstitution. Confederate artillery on Longstreet’s front had expended heavily and would need time to resupply. Both sides spent the night moving ammunition, replacing equipment, and repositioning guns for what both commanders expected would be the battle’s decisive action.
July 3 brought the culmination of everything the first two days had been building toward. Colonel Edward Porter Alexander, commanding much of Longstreet’s artillery, had assembled between 160 and 175 Confederate guns along Seminary Ridge. The intent was to concentrate fire on the Union artillery and infantry on Cemetery Ridge, suppress the Union guns, and disorganize the defensive line enough that infantry could break through it. It was a logical application of artillery preparation doctrine.
What Alexander could not fully control was what happened when more than 160 guns opened fire simultaneously in July heat and humidity, generating a smoke cloud so dense that from Seminary Ridge observation became nearly impossible. Artillery without accurate observation fires blind, and at ranges of twelve to fifteen hundred yards, small elevation errors translated into large errors in point of impact. The bombardment lasted nearly two hours and expended something close to twenty thousand rounds. It caused genuine damage on Cemetery Ridge.
It killed men and wrecked equipment. But in significant proportion it overshot its targets entirely, arcing over the crest and landing among the artillery reserve, ambulances, and supply trains behind the ridge. The Union position was battered. It was not broken.
Henry Hunt’s decision during those two hours changed the outcome of the assault. He ordered the Union artillery on Cemetery Ridge to slow its return fire and then cease it altogether. His reasons were precise. He wanted to preserve ammunition, and if the infantry assault was coming, he wanted full loads of canister available for every piece.
He also recognized that going quiet might convince Confederate observers that the Union batteries had been suppressed. When the Confederate infantry stepped off from Seminary Ridge and began the long walk across three-quarters of a mile of open ground, the Union guns that had gone quiet opened as soon as the Confederates came into effective range. Long-range fire gave way to case shot as the distance closed, and then to canister as the formations came nearer. The guns on Cemetery Hill, angled to sweep the line from the side, produced an enfilading fire that passed through the advancing formations lengthwise, each round reaching multiple men in sequence.
The assault columns that reached the low stone wall at the angle on Cemetery Ridge had crossed three-quarters of a mile of uninterrupted artillery fire. Perhaps five thousand men stepped off. Several hundred reached the wall. A smaller number went over it.
The men who briefly broke through under Lewis Armistead were too few and too disorganized by what they had crossed to hold what they had taken. The bombardment of July 3 did not fail through incompetence. Alexander was a capable officer who planned carefully. What defeated him was the smoke that obscured observation, the overshooting that wasted ammunition behind the ridge, and the decision of the opposing artillery chief to go quiet at exactly the moment Confederate observers needed Union fire to confirm that suppression was incomplete.
The carefully positioned, conserved, and managed Union artillery produced in those approximately eighty intact guns the precise defensive result artillery was capable of delivering when well led and well positioned on favorable ground. The artillery at Gettysburg shaped every critical decision of those three days, from the first gun that fired on Oak Hill on July 1 to the last canister round that stopped the Confederate infantry short of the wall at the angle on July 3. It determined what terrain was defensible and what was not, which assaults were viable and which were not, what the infantry on both sides could be asked to do and what they could not survive doing.
In those three days in July 1863, the guns of both armies demonstrated with a clarity that no subsequent argument could entirely obscure that the war everyone had arrived expecting to fight was already a thing of the past, and that what was actually happening in those Pennsylvania fields required a harder reckoning with what artillery had become and what it was capable of doing to men who had no choice but to stand in its way.