Then, deploying software used in the defense industry, she taps functions such as “triangulated irregular network” and “viewshed analysis” and something that “determines the raster surface locations visible to a set of observer features.” I’m simplifying here. Imagine pixels and grids swimming across the screen in response to keystroke commands that are about as easy to follow as the badly translated instructions that came with your last electronic device. “There’s a steep learning curve to GIS,” Knowles acknowledges.
What emerges, in the end, is a “map” that’s not just color-coded and crammed with data, but dynamic rather than static—a layered re-creation that Knowles likens to looking at the past through 3-D glasses. The image shifts, changing with a few keystrokes to answer the questions Knowles asks. In this instance, she wants to know what commanders could see of the battlefield on the second day at Gettysburg. A red dot denotes General Lee’s vantage point from the top of the Lutheran Seminary. His field of vision shows as clear ground, with blind spots shaded in deep indigo. Knowles has even factored in the extra inches of sightline afforded by Lee’s boots. “We can’t account for the haze and smoke of battle in GIS, though in theory you could with gaming software,” she says.
Scholars have long debated Lee’s decision to press a frontal assault at Gettysburg. How could such an exceptional commander, expert in reading terrain, fail to recognize the attack would be a disaster? The traditional explanation, favored in particular by Lee admirers, is that his underling, Gen. James Longstreet, failed to properly execute Lee’s orders and marched his men sideways while Union forces massed to repel a major Confederate assault. “Lee’s wondering, ‘Where is Longstreet and why is he dithering?’” Knowles says.
Her careful translation of contours into a digital representation of the battlefield gives new context to both men’s behavior. The sight lines show Lee couldn’t see what Longstreet was doing. Nor did he have a clear view of Union maneuvers. Longstreet, meanwhile, saw what Lee couldn’t: Union troops massed in clear sight of open terrain he’d been ordered to march across.
Rather than expose his men, Long- street led them on a much longer but more shielded march before launching the planned assault. By the time he did, late on July 2, Union officers—who, as Knowles’ mapping shows, had a much better view of the field from elevated ground—had positioned their troops to fend off the Confederate advance.
Knowles feels this research helps vindicate the long-reviled Longstreet and demonstrates the difficulties Lee faced in overseeing the battle. But she adds that her Gettysburg work “raises questions rather than providing definitive answers.” For instance: Lee, despite his blind spots, was able to witness the bloody repulse of Longstreet’s men that afternoon. “What was the psychological effect on Lee of seeing all that carnage? He’s been cool in command before, but he seems a bit unhinged on the night of the second day of battle, and the next day he orders Pickett’s Charge. Mapping what he could see helps us ask questions that haven’t been asked much before.”
Knowles says her work has been well received by Civil War scholars. But that’s partly because military historians are more open than others to new geographical techniques. Many historians lack the technical know-how and assistance to master systems like GIS, and are accustomed to emphasizing written rather than visual sources.
“The old school, in history and geography, dug up records and maps, but did not pay much attention to the spatial aspect of history,” says Guntram Herb, a colleague of Knowles’ in Middlebury’s geography department. “And there’s this lingering image of geography as boring and pointless—what’s the capital of Burkina Faso, that sort of thing.”
Knowles’ work has helped reshape this outdated image. To students who now arrive at college with computer savvy and familiarity with Google Earth and GPS, geography seems cool and relevant in a way it didn’t in my long-ago social studies class. Knowles has also brought GIS, once a fringe methodology mainly used by planners to plot transportation routes and land-use surveys, into the historical mainstream. And she’s done so by creating teams of scholars from different areas of expertise, which is common in the sciences but less so among historians. “Technical expertise, archival expertise, geographic imagination—no one has it all,” Knowles says. “You have to work together.”
This embrace of collaboration, and willingness to cross academic boundaries, stems from the unusual path Knowles has followed since her girlhood in Kalamazoo. If she were to map her own career, it would show loops and islands rather than a linear progression. At first, her love of family journeys through the American past didn’t translate into an academic interest in history. “I wrote poetry and loved literature,” she says. As an English major at Duke, she started a magazine and was also a talented modern dancer, which led her to New York City after college.