As a geographer at Middlebury College, I utilize digital technologies to explore and reinterpret historical events. Today, let’s journey back to Gettysburg, Pennsylvania, on July 1, 1863, during the American Civil War. This location became the unexpected meeting point for Confederate forces led by Robert E. Lee and Union forces under George Meade. Although neither side planned to engage here, the Battle of Gettysburg emerged as a pivotal moment in the Civil War.
Robert E. Lee is renowned as one of America’s most respected generals. However, at Gettysburg, he made critical errors, notably ordering Pickett’s Charge. To gain a fresh perspective on this event, I employed historical maps and Geographic Information Systems (GIS). A key resource was a massive 12 by 13-foot map housed at the National Archives, which I transformed into a detailed, poster-sized map. This map illustrates the town of Gettysburg, its varied terrain, forests, orchards, streams, and roads.
Before delving into the map, it’s essential to understand GIS, or Geographic Information Systems. This software allows for mapping and terrain analysis, such as determining the best views for a ski resort using viewshed analysis. I applied this technique to digitally step into Robert E. Lee’s shoes, asking, “What could he see?” and “What was hidden from his view?” These questions are crucial for understanding his strategic decisions.
The map’s fine black lines, known as contour lines, depict elevation at 4-foot intervals, offering incredibly detailed elevation data. By tracing these lines and assigning elevation values, I created a continuous terrain simulation of the battlefield using GIS. This allowed me to visualize the landscape as Lee might have seen it.
On the morning of July 3, 1863, Lee faced a critical decision. After two days of intense fighting with no clear advantage for either side, he sought a vulnerable point in the Union line. Using viewshed analysis, I determined what Lee could and couldn’t see from his vantage point. The grey areas on the map represent what was hidden from his view, while the clear areas show what he could observe.
John Bachelder, a landscape painter, documented troop positions at Gettysburg with remarkable precision. His work, funded by Congress, resulted in 24 maps that I digitized and integrated into the GIS. These maps are vital for understanding Lee’s limited visibility of Union troop positions.
Lee’s scouts failed to report a significant portion of the Union army east of the Roundtops. Consequently, Lee believed he was attacking a weak point in the Union line. However, he was unaware of the Union’s ability to reinforce this area quickly. As the Confederate soldiers advanced, the Union troops swiftly moved to strengthen their center, leading to fierce combat and ultimately driving the Confederates back.
This analysis of sight and visibility offers new insights into Lee’s decisions at Gettysburg. His actions, based on incomplete information, resulted in a devastating defeat. The story of sight also highlights the Union’s advantage. On the second day of battle, Union General GK Warren’s strategic positioning allowed him to spot Confederate movements and call for reinforcements, contributing to the Union’s success.
The 150th anniversary of the Battle of Gettysburg provided an opportunity to collaborate with a 3D animator, using GIS data to recreate the terrain visually. This project underscores the potential of digital technologies in historical research. I encourage those skilled in digital tools to explore their applications in history, as they can yield remarkable insights. Thank you for joining me on this journey through history.
Engage in a hands-on workshop where you’ll use Geographic Information Systems (GIS) to analyze historical maps of the Gettysburg battlefield. You’ll learn how to perform viewshed analysis to understand the strategic decisions made by generals during the battle.
Participate in a project to digitize historical maps, similar to the work done with John Bachelder’s maps. You’ll gain experience in transforming physical maps into digital formats and integrating them into GIS for further analysis.
Take part in a role-playing simulation where you assume the role of a Civil War general. Using digital maps and GIS data, make strategic decisions based on the terrain and visibility, and discuss the outcomes with your peers.
Work with a 3D modeling software to create a visual representation of the Gettysburg battlefield. This activity will help you understand the impact of terrain on historical events and the power of digital tools in visualizing history.
Conduct research on a specific aspect of the Battle of Gettysburg using digital technologies. Present your findings to the class, highlighting how digital tools enhanced your understanding of historical events.
I’m a geographer at Middlebury College, and I use digital technologies to reimagine the past. I want to take you to Gettysburg, Pennsylvania, July 1, 1863, right in the middle of the Civil War. From the northwest, the Confederate forces under Robert E. Lee and from the southeast, the Union forces under George Meade converge at this place more or less by chance. They didn’t plan to fight here, but the Battle of Gettysburg turns out to be the turning point of the Civil War.
Now, Robert E. Lee is probably the most famous American general, widely respected. But at Gettysburg, he made some crucial mistakes, probably the most important was in ordering Pickett’s Charge. I’m going to show you how I took a new look at Pickett’s Charge with historical maps and GIS. My key map was an extraordinary 12 feet by 13 feet map in the vault of treasures at the National Archives. Here are some of my students at Middlebury to give you a sense of that scale. It was recompiled into a finished map the size of a large poster. You can see the layout of the town of Gettysburg, the undulating shape of the terrain, forests, orchards, streams, and roads.
I want you to look at those fine black lines. Those are called contour lines, and they show the elevation at 4-foot intervals, the most detailed elevation I have ever seen. Now, before I explain this image, I need to tell you a little about GIS. It stands for Geographic Information Systems. It’s a kind of software that allows you to map almost anything and do terrain analysis. For example, if you’re building a ski resort and want people to have the most spectacular view possible, you use viewshed analysis to show what can be seen from a certain point on the terrain.
I used that to place myself digitally in the footsteps of Robert E. Lee, to ask, ‘What could he see?’ and ‘What could he not see?’ that might have influenced his command decisions. Now, back to these contour lines. This is the best elevation data that I could find. I traced all of the lines you see in the black and white drawings, stitched them together, gave them elevation values, and then transformed it within the GIS program into a continuous terrain. This is a simulation of the ground of the battlefield.
Now, I’m ready to place myself in Lee’s boots and ask what he could see. The particular moment I want to look at is Pickett’s Charge. Lee makes a crucial decision on the morning of the third day, July 3rd, 1863. The fighting on the previous two days has been fierce, and neither side has a clear advantage. Lee goes to the southern end of the battlefield at about 8:00 in the morning with his binoculars to figure out where to attack the Union line, where they are most vulnerable.
In this next image, I’m going to show you the GIS process called viewshed analysis. Along with Lee’s line of sight in that reddish cone is the direction we think he was looking. Viewshed analysis tells me what I can see and what I can’t see from a certain point, so in this map, the grey area is what Lee couldn’t see. The clear area, where you see that historic map coming through, is what he could have definitely seen. Notice how much of the right side of the map is in grey.
Now, we add another crucial piece of information. Someone named John Bachelder, a landscape painter from New Hampshire, went down to the battlefield to document where troops had been and to try to paint the battle. He ended up getting funding from Congress to document troop positions down to the half hour. He produced 24 maps that we also digitized and brought into the GIS. This next map shows that troop position information; it’s crucial for understanding what Lee could and couldn’t see.
If you look closely at this map, you might see a black oval around an area that’s relatively clear. The blue markings in that black oval are Union troops that I’m sure Lee could see. But if you look to the right of that, you’ll see many blue markings. Those are Union troops in the shadows. We know that on the night before Lee’s reconnaissance, he sent out scouts to find out where the federal troops were. Astonishingly, the scouts came back saying, ‘Don’t worry, General Lee. We didn’t see any troops to the east of the Roundtops.’ We don’t know if they got distracted or missed them, but they didn’t see almost a third of the Union army.
So, Lee is blind from his scouts, and from his viewpoint, he’s also blind. He decides to attack what he thinks is the weak middle of the Union line, not knowing where the rest of the troops are. In the middle of this image, there’s a gap in the Union line from where the blue soldiers are at the north of the battlefield and at the south.
Let me now play out, using these troop positions, Pickett’s Charge. The Confederate soldiers are lined up on the west side of the battlefield, standing under the trees. 18,000 men begin to walk, then trot, and then run across open farm fields with their rifles leveled at the federal line. The Union army has about 15-20 minutes to organize itself. They see that the Confederates are converging on the middle of their line, and what do they do? The blue arrow here represents the movement of the Union troops; they pull their troops toward that weak center.
Lee didn’t know that the Union could have done this. Now, they’re standing like a wall, ready to receive the Confederate assault, which happens between 1:30 and about 2:30 in the afternoon. There is fierce fighting, hand-to-hand combat. The blue lines coming in between 2-2:30 in the afternoon are pulling more reserves, more reinforcements to that weak center of the Union line. What happens? The Union soldiers drive the Confederates off. Lee rides out among his men at 3:00 in the afternoon, saying, ‘I’m sorry. It’s my fault.’
This story of sight has been a missing part of the Battle of Gettysburg. Historians have not been able to figure out what he could and couldn’t see. I think it helps explain his decision. From his point of view, the federals were very weak. He was attacking at the logical place, but without full knowledge, he set his men out for a dreadful defeat.
Now, there’s one more piece to this story. Last summer was the 150th anniversary of the Battle of Gettysburg, and I was able to work with a 3D animator to use the GIS information to render the terrain issue as you see it here. My closing story is about how sight helped the other side. A federal general named GK Warren stood in the spot that this panoramic view is showing you, looking out over the battlefield. At a key moment on day two, he was able to see Confederate soldiers emerging out of the trees who were about to attack Little Roundtop. He called in reinforcements just in time and saved the day for the Union, setting the stage for the Union’s almost-victory on day three.
So, I hope that all of you who are gifted with digital technologies will begin to think about how you can use them for history. It can be amazing. Thank you.
Geography – The study of the Earth’s physical features, climate, and human-environment interactions. – Geography helps us understand the spatial relationships between different regions and how they affect human activities.
History – The study of past events, particularly in human affairs. – Understanding history allows us to learn from past civilizations and their impact on modern society.
Battle – A military conflict between opposing forces, often part of a larger war. – The Battle of Hastings in 1066 was a pivotal moment in English history, leading to Norman control of England.
Terrain – The physical features of a tract of land, including its elevation, slope, and vegetation. – The rugged terrain of the Andes Mountains poses significant challenges for transportation and settlement.
Visibility – The distance one can see as determined by light and weather conditions. – During the naval battle, poor visibility due to fog significantly affected the commanders’ strategic decisions.
Analysis – The detailed examination of elements or structure of something, typically as a basis for discussion or interpretation. – The analysis of historical documents can provide insights into the cultural and political climate of a particular era.
Technology – The application of scientific knowledge for practical purposes, especially in industry. – Advances in satellite technology have revolutionized the way geographers study and map the Earth’s surface.
Maps – Visual representations of an area, showing physical features, political boundaries, and other significant details. – Historical maps can reveal how perceptions of geography and territorial boundaries have changed over time.
Decisions – Choices made after consideration of various factors and possible outcomes. – Strategic decisions during the war were heavily influenced by the geography of the region and the availability of resources.
Insights – Deep understanding of a complex situation or problem. – Insights gained from archaeological findings can shed light on the social structures of ancient civilizations.
