A New Perspective on Gettysburg
#American Civil War
Anne and her students were asking an old question, a question historians have been pondering for decades: Why, on July 3, 1863, did Lee order Pickett's Charge? Why did Lee order his men to march across open fields in broad daylight towards a well-fortified army?
While teaching at Middlebury College in Vermont, Anne had her students study The Battle of Gettysburg using Geographic Information Systems (GIS). GIS is a powerful program that can make beautiful yet highly intelligent maps. They brought a fresh perspective to the famous battle, a battle that was a turning point in the Civil War.
In the Vault of Treasures in the National Archive, there is a 12’ x 13’ map of Gettysburg made by the Army Corp of Engineers between 1868 and 1869. Using photocopies, Anne’s students laid out the 20 map sections on a floor where they could stand over it, walk on it, and study it. This poster-size, detailed digital reimaging, served as their base map. Now the challenge was getting that data into the GIS program. The four-foot contours had to be traced by hand onto mylar, scanned into GIS, and transformed into a network of triangles, giving the map a continuous terrain and the appearance 3D. All this while maintaining accuracy. Easier said than done.
Around 8:00 a.m on July 2, from the cupola of The Lutheran Seminary, a little north of the center of the battlefield, General Lee, with binoculars in hand, surveyed the battlefield through a haze of gun and cannon smoke. He had a good view, especially to the south and northeast. Using GIS and a program called Viewshed, Anne and her students were able to place themselves digitally in the shoes of Robert E. Lee and see what he could see, and, more importantly, what he could not see.
The Viewshed tool creates a cone of sight from Lee’s perspective, shading the areas Lee could see and not shading the areas he could not see. You could use this same program to determine, for example, the optimum building site for a house or resort. Viewshed would shade the areas you could see, let's say from your porch, and not shade areas that would not be visible, helping you build where your view would be maximized. But in the context of Historical GIS, Viewshed provides a new perspective and insight into Lee’s decision.
Shortly after the battle of Gettysburg, John Bachelder, a landscape painter from New Hampshire, visited the battlefield and created 24 detailed maps of troop positions to within a half an hour of each other. Anne and her students added this layer to the GIS map. This allowed them to determine that hidden from Lee’s view atop The Lutheran Seminary on July 2, were reinforcements massing to the southeast, as well as troops to the east and northeast.
On the morning of July 3, around 8:00, Lee took a position from a hill known as Round Top, on the southern end of the battlefield. This is when he made his fateful decision to order an attack on the Union army, a battle known as Pickett's Charge. This time Viewshed reveals that Lee’s field of view had dramatically decreased. He saw far less than he had seen the day before from The Lutheran Seminary.
Just to Lee’s east, on the other side of Round Top and Little Round Top, thousands of Union troops were out of sight, as were troops to his north and northeast. These were the men that would eventually fill what appeared to be a weak middle. Nearly one third of the Union Army was hidden from Lee’s view.
There were no drones or satellites to provide Lee, Meade, and the other generals with intel. Success in battle depended on their vision and knowledge of the terrain. Lee and Meade had both studied topographical mapping and engineering at West Point. Lee especially was a skilled topographer, having spent time surveying the Mississippi River and working on other projects. He knew the importance of reading the terrain, and he knew, going into battle at Gettysburg, he was fighting on ground that had been poorly mapped. He would have known he lacked the necessary geographical information to make good decisions.
Yet all the troops, Union and Confederate, were in relatively close proximity, so any good reconnaissance team should have come up with a rough estimate of the size and location of the enemy. That didn’t happen. Scouts told Lee, on the night of July 2, there were no other troops to worry about.
From a new position, behind his troops, in the early afternoon of July, 3, Lee watched as 18,000 men under the command of General Longstreet began their march to the east, towards an open area between Cemetery Hill and Cemetery Ridge. The Union army, commanded by General Meade, waited for them. Federal troops quickly closed the gap and reinforced their middle as confederate soldiers advanced.
Pickett and his men, who had been under cannon fire all morning, saw this happen and veered left, to the north, leaving their right flank vulnerable. The 2nd Vermont Brigade took full advantage of the exposed flank, inflicting heavy casualties on the confederates. In the end it probably didn’t matter that Pickett chose to move north, away from the center, rather than make a direct assault to the west, as he had been ordered. In both instances Pickett and his men were terribly outnumbered and out maneuvered.
General Lee made his way to The Lutheran Seminary. His mistake may simply have been lack of patience, on this third day of the bloodiest battle in American history. Everyone wanted it to end. By 3:00 Lee was visiting his troops. As he viewed the carnage, listening to the agonizing cries of the wounded, he apologized, saying, “This was all my fault, General Pickett. This has been my fight and the blame is mine. Your men did all men can do. The fault is entirely my own.”
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Conversely, sight helped the Union Army. Using digital rendering software, Tim Montenyohl at Mapping International, made a panorama of the battlefield, creating a landscape similar to what existed on July 3, 1863. Tim shows, from the perspective of Union General G.K. Warren, that on day two, Warren was able to see confederate troops massing on the horizon to the west, getting ready to attack Little Round Top. Warren called in reinforcements that of course Lee could not see.