Historians have spilled more ink about the Battle of Gettysburg than any other conflict in human history. Still, people often lose sight of the critical role artillery fire planning played in the attack against Cemetery Ridge.
Confederate Fire Support Plan
When General Lee decided to attack Cemetery Ridge on July 3, he fashioned a plan
that depended on a massed artillery preparation. He intended to have the artillery fire pave the way for Pickett’s, Pettigrew’s and Trimble’s infantry divisions. Yet, Lee’s plan fell short of its potential. Lee's Army had not developed the degree of centralized fire planning necessary to achieve his purpose. The army’s chief of artillery, Brigadier General William Pendleton, viewed his role as a logistics planner, not as a tactician. He only contributed to the fire support plan by tasking the batteries in Hill's and Ewell's Corps that faced the objective to join the bombardment. Responsibility for directing the artillery fire against Cemetery Ridge devolved upon Colonel Edward Porter Alexander who commanded the I Corps (Longstreet's) artillery reserve battalion. Alexander amassed enough guns to pound Cemetery Ridge. Eighty-four guns from I Corps, seventy-two guns from III Corps and another sixteen from II Corps would fire the preparation.
The batteries deployed along Seminary Ridge that ran parallel to the objective on Cemetery Ridge. The guns had a broad sweep of the Union lines but the limited depth of the objective presented a challenge. The gunners needed precise range estimates and accurately timed fuses to strike their targets. Lee counted on the 172 guns to soften up the Union infantry and take out their supporting artillery. However, the Confederate fire support had one inescapable limitation. Lee had planned a frontal attack. The Confederate infantry had to pass through their own artillery batteries on the way to the objective. That meant the artillery could not suppress the Union guns during the infantry approach march and final assault.
The Confederate fire support plan had another, needless, flaw. Neither Lee nor
Pendleton planned artillery fire to encompass the whole battlefield. More than 40 guns belonging to Ewell's II Corps stayed idle during the attack. Pendleton left them out of the battle because II Corps was not involved in the attack. This decision violated an important artillery precept to maximize the use of available fire support assets.
To make matters worse, the II Corps guns had the best position for suppressing the defenders on Cemetery Ridge. The Union defense resembled a fish-hook, anchored on Round Top in the south and Cemetery Hill in the north. The long dimension of the front ran north-south along Cemetery Ridge. The south-facing II Corps guns had a chance to rain devastating enfilade fire down the length of the objective. The gunners only had to align their guns with the ridge and not worry about the range. Their shells would land somewhere along the defensive front. Furthermore, these guns could keep firing throughout the infantry attack until the final push masked their fire.
Union Fire Support
In contrast, the Union chief of artillery, Major General Henry Hunt, supervised all the army’s guns. He even oversaw the allocation, positioning and targeting of the guns under the direct control of the corps commanders. Hunt arrayed his batteries from Little Round Top in the south to Cemetery Hill farther north. From these positions, Union artillery covered the valley separating the two armies with deadly interlocking fire. Hunt also trained his battery commanders to fire at a deliberate rate to conserve ammunition and preserve accuracy.
The effectiveness of the artillery fire on July 3, 1863 reflected the tactical expertise of the two artillery chiefs. The Confederates unleashed a concentrated and sustained bombardment but the massive preparation failed to blast a hole in the Union line. The gunners had difficulty setting the proper range on their guns. As a result, the shells mostly overshot the objective.
At first, the Union batteries returned fire, leading to an indecisive artillery duel. Union General Hunt intervened to stop the duel. He ordered his batteries to cease fire. He knew the upcoming infantry attack represented a greater threat and a more lucrative target for the Union’s remaining rounds. Across the battlefield, Colonel Alexander halted the Confederate preparation once ammunition ran low. This left the Confederate infantry to break the Union line on their own. A key piece of Lee’s battle plan had fallen short.
When the Confederate infantry divisions approached Cemetery Ridge, the Union guns inflicted appalling casualties with canister shot against the exposed infantry. Rather than stay put, one aggressive Union battery surged forward and flanked the Confederate formation. Their guns then shattered the attacking infantry with deadly enfilade fire. As the attack reached its decisive stage, the Union guns punished the Confederates with heavy losses.
To read a more detailed description of the assault on Cemetery Ridge, I invite you to read my previous publication, More Terrible Than Victory,
In sum, ineffective Confederate artillery fire planning squandered a chance to deliver a damaging blow to the Union position on Cemetery Ridge. This oversight allowed well-planned and well-managed Union artillery fire to cripple the assault.