This week’s readings in Placing History concerned the uses GIS could have for historians. For me, the example that struck home the most concerned the last chapter, entitled “What could Lee see at Gettysburg?” I have been interested in the Civil War for as long as I can remember, and so I found the spatial maps outlining just what would be visible from various areas of the battlefield extremely interesting, as they helped to explain some of the more outlandish decisions made by commanders during the second and third days of the battle. (I am also admittedly a fire-breathing Yankee, a position I have discovered is not that popular in the South…but that story another time.)
Some quick background: after fierce fighting on July 1, the first day of the battle, Union forces had retreated through the town of Gettysburg and set up defensive positions along the heights of Cemetery Ridge to the south of town. General Lee, the Confederate commander, decided to attack the Union flanks on July 2, sending one of his best commanders, General Longstreet, to attack the Union left.
Longstreet has since been severely criticized for his failure to turn the Union left that day, especially after the massive opportunity given to him by Union General Sickles, who moved his Third Corps from Cemetery ridge to slightly higher ground in front, putting him away from any possibility of support and resulted in the near-destruction of Third Corps and the savaging of the Union Fifth Corps as they were rushed to fill the breach. The major criticism of Longstreet’s performance on the second day regards him moving his troops back and forth for most of the day before moving forward. Many historians through the years have contended that had Longstreet simply moved forward instead of this shifting his troops back and forth, they may have turned the Union left before Fifth Corps could take position, possibly resulting in a Confederate victory. Lacking any possible explanation for this random shuffling, some historians have simply regarded it as Longstreet’s hand-wringing, using it as evidence in a claim that Longstreet betrayed the Confederacy.
It is amazing how such a baffling question becomes so simply obvious when applying a line-of-sight layer over a Gettsburg map through GIS. On the far left of the Union line was a small unnamed hill, later known as Little Round Top. Little Round Top held a domineering view over much of the Gettysburg battlefield, but it is only through the magic of GIS does it become clear just how domineering that view was. The area of the Confederate line where Longstreet’s men were forming could clearly be viewed from Little Round Top, and no matter where Longstreet moved he could still easily see Union soldiers with signal flags on the hill–and thus they could theoretically see him too. Longstreet’s baffling shuffling back and forth could suddenly be easily understood: he was searching for a line of advance where his troops would be hidden from the signalers so that he could take the hill before the signalers could call for help. Longstreet’s reluctant move forward late in the day was not resignation to follow the orders of the great Robert E. Lee, but resignation that there was no line of advance that would not be hidden from the signalers. (See figures 10.10, 10.11A, and 10.11B on pages 255-257.)
However, the historical record holds that the Union signalers did not see Longstreet’s troops until it was almost too late. Given the new evidence from the GIS map, how is it possible they could be so blind? The answer comes by adding one detail to the GIS map: vegetation. Adding in the forests around the area, and accounting for them blocking line-of-sight, the view from Little Round Top becomes much more restricted, particularly the wooded approaches to Little Round Top through which the Confederates advanced. Despite Longstreet’s fears, his advance on Little Round Top was in fact almost unnoticed. However, Longstreet’s hesitation, and the unnoticed advance, were not treason or blindness on the part of Longstreet or the signalers, simply the tricks of the terrain and incomplete information. (See figure 10.12, page 258.)
The vegetation map on page 258 also gives explanation to one of the other dramatic moments of the battle on July 2: the discovery of Longstreet’s forces by the Union. Learning of Sickles’ error, and able to hear the savage fighting on the Union left, Union commander General Meade sent one of his aides, General Gouvernour K. Warren, a former Army Engineer, to investigate. Warren arrived on Little Round Top to find it unoccupied save for the signalers and a small Union artillery battery in front of the hill, firing in support of Sickles’ collapsing Third Corps, whose plight was easily visible from the heights. The engineer in Warren immediately recognized the importance of the hill, and worried that not all the Confederate troops were drawn to encircle Sickles’ battered command. Acting on a hunch, he ordered the artillery battery to fire a shell over the top of the small woods in front of Little Round Top. The battery complied, resulting in one of the dramatic moments of the Battle of Gettysburg.
As Warren feared, the woods were filled with advancing Confederates, who had managed to remain unseen despite Longstreet’s fears. But as the artillery shell screamed over the treetops, the soldiers instinctively looked up, and the sun caught on the metal of their rifles. To Warren on Little Round Top, what had looked like woods and greenery suddenly gleamed with the reflections of Confederate muskets and bayonets.
History has well recorded what came next. Warren’s frantic search for Union reinforcements to hold the hill, the piecemeal rush of the Union Fifth Corps to take position, some units arriving with barely enough time to form their lines before coming under attack, the desperate attempt and brave heroism of Union officers and men to hold the line at all hazards. The fight around Little Round Top has become one of the defining moments of the Battle of Gettysburg, and it all came down to geography and line of sight. The magic of GIS allows us to see the field of Gettysburg in ways we never could before, and lets us gain a greater understanding of the battle than ever before.