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Make Straight His Path: Mapmaking in the Civil War

By Earl B. McElfresh
8/29/2018 • Civil War Times Magazine

Combat commanders may have gotten all the glory, but they might have never had their chance to shine if not for intrepid mapmakers and topographers who showed them the way.

One fine day in early spring 1862, Lieutenant George Armstrong Custer found himself hovering 1,000 feet above the rich red soil of the Virginia Peninsula. A reconnaissance flight in a huge hot air balloon was a scenario the young officer had never envisioned in his wildest dreams, and a certain amount of anxiety colored his outlook as he ascended in the seemingly frail willow basket that reached just above his knees. Civilian aeronaut James Allen was along for the ride, having asked the young West Point graduate whether he wanted company or to go up alone. Recalling the experience later, Custer said he had feigned indifference and “intimated” that Allen “might go along.” As the balloon floated ever higher, however, Custer began to have serious misgivings about the construction of the gondola and the sturdiness of its floor. The aeronaut sought to reassure his companion, jumping up and down in the basket to demonstrate its strength. That did nothing to allay Custer’s concerns, but his uneasiness quickly gave way to amazement. The peninsula, with the James and York rivers far below and the broad Chesapeake Bay in the distance, presented a vista to the young officer that almost no one else on the planet had ever seen before.

Gradually Custer grew accustomed to the balloon and the altitude and settled into the job at hand: making maps. He pulled out a pocket-sized notebook, a pencil, his compass and a pair of field glasses. The balloon’s swaying made it difficult for him to focus on the Rebel encampments in the distance, but the surrogate topographical engineer was able to see for miles, and he began translating what he saw into a military map. West Point had taught all its cadets how to map and draw, so Custer already had a good sense of what was expected of him. His military education also had prepared him to understand what he was seeing and recognize its significance to the Army, unlike civilian balloonists of the day, who usually did not know the difference between an abatis and a barbette. The young lieutenant carefully sketched details such as woods, streams, roads, terrain features, tents, artillery and fortifications. The quality of his maps was good enough and his observations astute enough that he was sent up several more times to map and assess the enemy’s positions and probable intentions.

The Union Army of the Potomac badly needed the data Custer was supplying, since Maj. Gen. George B. McClellan’s optimistic Peninsula campaign had gone awry almost from its beginning in early April. The campaign was good enough in theory, but it had relied on a map prepared by noted engineer Thomas Jefferson Cram. Without having access to the enemy-occupied ground, Cram drew an impressive map based on every resource he could find—including schematics prepared during the Revolutionary War siege of Yorktown. He also had used coastal maps prepared by the U.S. Coast Survey, the nation’s premier civilian map agency.

McClellan studied Cram’s chart and based his strategy on it. Fundamentally, the idea was for the Army of the Potomac to advance up the peninsula with its left flank resting on and protected by the Warwick River. Unfortunately for the Federals, Cram got the route of the river wrong. The Coast Survey had only mapped the waterway near the coast, where it ran parallel to the peninsula. Inland, it turned across the peninsula— so in reality the Warwick was impeding the Union advance, not protecting it. That was the first snag in a campaign that eventually unraveled completely.

The muddle on the peninsula was not confined to the Union forces, however. Confederate Brig. Gen. Richard Taylor later admitted that the Rebels knew no more about the topography in the immediate vicinity of their own capital at Richmond than they did of Central Africa. The confusion was paramount. Place names, for example, tended to be spelled erratically. One road listed as Darby was pronounced “enroughty.” Grandiose sounding locales such as Charles City often consisted of little more than a house and barn. Multiple names were even given to one location: Cold Harbor was also listed as Coal Harbor, Cool Arbor, Old Cold Harbor and Burnt Cold Harbor. Different roads in the same place had the same name. This topographical confusion was one factor that contributed to Maj. Gen. Thomas J. “Stonewall” Jackson’s mysterious, almost comatose performance during the Peninsula campaign, which occurred right on the heels of his phenomenal success in the Shenandoah Valley.

Early in the war there had been debate in Confederate circles about whether maps were even wanted, the rationale being that they could be captured and might ultimately be more useful to the Yankee invaders than the Southern defenders. Assorted fiascoes in defending the Virginia Peninsula, however, convinced General Robert E. Lee that a mapping department was essential.

The Union had an advantage in this regard because the infrastructure of the various federal mapping agencies was preserved. Their buildings, supplies and files, as well as their personnel, remained in Washington, D.C. Although their efforts had to be redirected and redoubled, their capabilities were almost completely intact. At the Winder Building, headquarters of the Topographical Engineers Department, the installation of heavy shutters completed the preparations for war.

The Confederates in Richmond faced a much more daunting challenge. They had no mapping organization, no supplies of any sort (the capture at one point of a large roll of tracing paper for copying maps proved a godsend to Rebel mapmakers) and no one to direct things—that is, until a civilian working in the Confederate Post Office, Albert H. Campbell, was tapped for the job. Campbell had plenty of engineering and surveying experience from his days of laying out routes for various railroads. Commissioned a captain and assigned to head up the Topographical Department of the Provisional Engineers Corps, Campbell was initially surprised to discover that no worthy maps were available at Army headquarters. Despite standing orders to the contrary, copies of maps prepared in the field were seldom forwarded. Campbell made sure that the surveying parties he fielded would not be interfered with or distracted from their duties by division and regimental officers. He also provided specific instructions as to the content of the maps they were to prepare. Particular attention was to be paid to the names of important roads, creeks and streams, churches, crossroads, bridges, ferries and fords. Engineers were also ordered to certify the local names of terrain features by interviewing nearby residents.

The demand for map copies quickly became overwhelming, and it was impossible to keep pace by tracing existing maps. Campbell claimed to have pioneered the technique of copying maps by a photographic method known as sunprinting. His office gradually became a map bureau and a repository for engineers in the field, and Campbell was able to supply the Confederate armies with good county and regional maps. Individual topographical engineers who actually campaigned with the armies prepared the more detailed route and tactical maps that guided the day-to-day planning and movement of the troops.

Although the call for reliable military maps was pressing for the Confederacy, it was profound for the Union. The Federal armies almost always fought on unfamiliar ground in the midst of a hostile population—that was the first difficulty Lt. Gen. Ulysses S. Grant listed when he prepared his postwar report for Secretary of War Edwin Stanton in July 1865. Poignant accounts of Southern soldiers dying at their own doorsteps also tell a revealing tactical story. Within their marching ranks, the Rebel armies had men who knew every inch of the ground they operated on; knew every bridal path, fording site, forest, well, orchard, general store, blacksmith, tavern, wheelwright, gap, pass, hollow, bridge and knowledgeable resident, all things that could be critical to the success of a maneuvering army. Rarely was any of that information known by a Union soldier, and it could only be gathered dangerously and slowly—if it could be gathered at all.

The few extant published county and state maps were typically inaccurate and showed little of the terrain and cultural data that an army needed to plan and conduct field operations. The only relevant maps the Union Army possessed were either disparately compiled, like the Cram map, captured or made when Union engineers took matters into their own hands, mounting their horses and moving carefully along Southern roads, transcribing local knowledge onto a map.

Civil War armies were especially vulnerable to conditions on the ground because of their size. The armies were usually too large to march in a body along a single road. Once an army began to move along parallel roads toward a single objective, a good map obviously became vital. The separated units had to stay within supporting distance of one another, so practicable intersecting roads had to be located. Enough water, food and forage had to be available along each road to sustain the troops and animals as they moved. The surface of each road had to be firm enough to support heavy wheeled vehicles. Those vehicles could not cross a ford that was much more than 2 feet deep because the wagon beds had to stay dry. The stream bottom had to be smooth and firm, and the ford needed to have gently sloping banks for easy passage. If at any point the road grade became too steep, wheeled vehicles could move neither up nor down them. All of those features had to be known in advance to ensure that forces arrived in good condition when and where they were needed.

The size of the armies also meant that a single passage by tens of thousands of men and animals made that route a wasteland for the foreseeable future. The roads were wrecked by the wagons, the larders emptied, the wells drunk dry, the fields stripped bare, the orchards picked clean and the fences torn down. The devastation was complete, and it made very little difference whether the army passing through was friend or foe. An army on the move had no time for niceties, and its voraciousness highlighted its vulnerability. An army in the sparsely populated countryside of mid-19th century America could not halt long without starving itself out.

One of the odd and often remarked-upon features of Civil War military maps was the inclusion of the names of residents along the roads. The topographical engineers took great pains to get those names right and printed on their maps. The names served two purposes. Especially in the South, roads were often rudimentary at best. Dry streambeds sometimes doubled as roads, and travelers noted that the only way to navigate some roads was to follow the telegraph poles. The roads were haphazardly named, and few of the people living along them could supply helpful directions, assuming they were willing to in the first place. If they could not give the way to the next town, though, they could at least point the way to their neighbor’s farm. The names thus served as route markers and road signs for the myopic armies. The number of residences also indicated the population density of a region. More inhabitants could supply more soldiers.

Pinpoint accuracy, however, was rarely the primary concern with campaign maps. A map was most valuable if it was timely and contained the requisite information— exact distances and perfect scales were luxuries. Civil War armies always fought within sight of each other, and approximate distances were satisfactory. Mapmakers learned to estimate distances by studying distant objects of familiar sizes (farm animals, fence posts, barns, steeples, the fact that a single pane in a mullioned window was distinguishable at 500 yards), and they used their horses’ steady paces as a scale: “1,050 horse paces equal one inch” was not an unusual notation on sketch maps.

Traditionally, the top graduates at West Point went into the U.S. Engineer Corps. They designed forts, canals and bridges, and they also prepared maps. The less prestigious artillery and infantry assignments awaited the lower-ranking graduates. When actual fighting erupted, however, the officers leading troops in combat gained the renown—as they always have—and rapid promotions. Bureaucracy being what it is, the topographical engineers, whose indispensable maps and counsel often made the difference between victory and defeat, were designated as officers leading small field parties. They were accorded the rank of major, captain or even lieutenant while their infantry and artillery classmates were becoming colonels and generals. For nearly all the career Army engineers, the lure of fame, rank and pay was irresistible. Engineers who opted for field commands often did well, including such luminaries as Gouverneur K. Warren, George G. Meade, Andrew A. Humphreys, John Pope, James B. McPherson and James H. Wilson. The Confederate roster of engineers who took field commands is even more impressive, with names such as Robert E. Lee, Joseph Johnston and P.G.T. Beauregard.

With so many engineers being lured away to other branches of service, much of the mapmaking was done by self-taught topographical engineers, or individuals who happened to have read a manual on mapmaking and suddenly found themselves with orders to begin making maps. Jedediah Hotchkiss, the war’s best-known topographical engineer, is typical of these men. A New Yorker turned Virginian, Hotchkiss created beautiful maps very quickly—but they were more attractive than accurate. He was invaluable as an aide to Stonewall Jackson, an aggressive but geographically challenged general. Hotchkiss’ expertise was his ability to produce largescale (showing small areas in great detail) military maps on the spot for his command and employing them to explain the tactical benefits of the topography. Using colored pencils to differentiate the cultural and physical details and drawing very vivid pictorial terrain features, Hotchkiss created diagrams that Jackson could easily comprehend. The hills were rendered with hachure marks— eyelashlike lines that mimicked the sloping sides of elevations—and trees were drawn as in a landscape. With Hotchkiss at his side, Jackson could visualize his ideas, interrogate his topographer and design his battle plan with confidence.

Comparing a typical county wall map from the period with one of the military maps that Hotchkiss prepared makes it clear why topographical engineers were so essential to Civil War commanders. An 1858 map of Adams County, Pa., that was used by both sides during the Gettysburg campaign was professionally surveyed and contains a large-scaled detail of the county seat, Gettysburg. But this excellent map failed to illustrate any of the topographical landmarks of the battlefield: no Wheatfield, Devil’s Den, Seminary Ridge, railroad cuts, Cemetery Ridge, Little Round Top, etc. The single unaccountable exception was Sherfy’s peach orchard. The lettering for “GETTYSBURG” obscured much of the area where the first day’s fighting would unfold. Missing were the preternatural sites that veteran commanders and individual soldiers selected when their options narrowed under the duress of combat. A sunken road, a slight knoll, a sheltering cornfield or a fence corner were the nondescript features that the soldiers drifted toward, ducked behind or clustered around. Their presence brought other soldiers, and the convergence of action established a battlefield landmark.

It was the business of the topographical engineer to anticipate those sites if possible, and to use them if necessary. Confederate engineer William W. Blackford, who served most of the war on cavalry commander J.E.B. Stuart’s staff, made a practice of studying the wreckage of a battlefield before the casualties had been moved. His object was to study the terrain in relation to the killed and wounded so as to understand under what circumstances the most damage could be inflicted on the enemy.

An engineer’s advice could be specific, as when Union general and topographical engineer Gouverneur Warren ordered troops to hold Little Round Top at Gettysburg on July 2, 1863, or it could be general, as when Hotchkiss warned Jackson that his bivouac at Narrow Passage in the Shenandoah Valley was unsafe because roads led to the flanks and rear of the camp. Perhaps the most complete topographical failure of the war occurred during Confederate General Braxton Bragg’s defense of Missionary Ridge near Chattanooga, Tenn., in November 1863. Bragg deployed his forces along the “physical crest” of the ridge rather than along the distinctly different “military crest.” From the physical crest, large sections of the slopes leading up the side of the ridge were invisible to the Confederate defenders. These blind spots became, in effect, safe zones for the Union infantry advancing toward the ridge. Thus Bragg had created a scenario in which it was safer for the Union troops to advance than to retreat or halt. The proper arrangement of Rebel forces would have been along the military crest, along the slopes of Missionary Ridge, where they could see and bring fire to bear on every point to be defended and also monitor every step of the enemy’s progress. Bragg’s error cost him the battle, his command and the state of Tennessee.

Even legendary generals such as Robert E. Lee sometimes were oblivious to the dictates of topography and necessity of maps. Lee was blindsided throughout the Gettysburg campaign by map-related failures. His crossing to the north side of the Potomac River marked a sea change in his military environment. Leaving the familiar terrain and friendly population of Virginia thickened the fog of war for Lee’s army. Growing uncertainty caused him to drift to a halt at Chambersburg, Pa., on June 28, 1863. Instead of having the eyes and ears of every patriot in Virginia to keep him informed about enemy movements, Lee was forced to rely on the report of one seedy scout. A flustered and fretful Lee is not a familiar image, but there is abundant testimony that such was his state of mind as he groped somewhat blindly toward Gettysburg.

Meade, Lee’s Union counterpart, had been a topographical engineer in his antebellum career. He tended to respond to military situations with the intellectual detachment typical—and desirable—in an engineer. In one respect that worked out well for the Union because unlike his predecessor, Maj. Gen. Joseph Hooker, Meade was not mesmerized by Lee. Before he was relieved as commander of the Army of the Potomac on June 27, 1863, Hooker made it clear that he would do anything, go anywhere and fight any body, so long as it didn’t involve Lee.

Meade had his own obsession: terrain. He found the perfect ground on which to confront the Rebels along Pipe Creek, just south of the Pennsylvania border in Maryland, and he was loathe to give it up. Meade proceeded reluctantly to Gettysburg after the first day of fighting when it became clear that the battle was not coming to him. He was guided to the field along the darkened Pennsylvania roads by his favorite topographical engineer, William Henry Paine, another selftaught topographer like Hotchkiss. Like other resourceful Americans of his time—including Abraham Lincoln and Henry David Thoreau—Paine had taught himself surveying because the job paid fairly well. Once at Gettysburg, Paine led Meade along Cemetery Ridge. With a drawing board on the pommel of his saddle, Paine noted the troop dispositions Meade desired as he sketched the basic terrain. The resulting map was copied and distributed to Meade’s staff and commanders. Some in the Army of the Potomac believed that Meade consulted more frequently and at greater length with Captain Paine than with any of his other staff officers or corps commanders.

Paine was an indefatigable mapmaker. In fact, during the Appomattox campaign in April 1865, he rode into a swirling crowd of armed Rebels and zealously mapped what he could in the event that surrender talks broke down.

Hotchkiss and Paine were typical of the adaptable civilians who adjusted their talents to military purposes and consulted, guided and mapped for the armies in the East. The Federal armies in the West tended to rely on more formally trained Army and U.S. Coast Survey mapmakers. Major General William S. Rosecrans arranged a dedicated department for mapmaking and shielded its staff from outside interference. The result was the most efficient and effective map operation on either side during the war. This was the department that Maj. Gen. William T. Sherman inherited—and replicated in each of his three armies.

Men such as Orlando Poe, William Merrill and their junior officers, including Ambrose Bierce, John Rziha and William Margedant, provided the topographical foundation for the war Sherman was building. As the general planned his campaign from Chattanooga to Atlanta, his engineers worked diligently to find extant maps of the region and to gather topographical information. There were men such as Sergeant N. Finegan of the 1st Ohio Cavalry whose specialty was interrogation. He questioned anyone who might have knowledge of the territory ahead. Finegan was apparently pleasant, a good conversationalist and a fine listener. He talked with deserters, prisoners, preachers, country doctors, peddlers and other locals likely to be familiar with local roads, byways and shortcuts. The sergeant would carry on a conversation, asking harmless, affable questions to get his subject feeling comfortable about talking—and answering. Then he would slip in seemingly innocent questions about roads and mountain passes. He would get the addresses of county surveyors and the location of the county courthouse, both good resources for maps. Others like Finegan would go up on the picket lines and join in the good-natured ribbing and chitchat that often occurred with the Rebel pickets. Some of that careless gossip provided invaluable intelligence, and the sites along the rivers where there were exchanges of tobacco for coffee showed the engineers where the fords were located. Among the intelligence jewels they picked up was the existence of Snake Creek Gap, which became the linchpin of the first phase of Sherman’s Atlanta campaign.

The best, most reliable extant map served as a “basis” map and was used to create a “skeleton” map. The principal geographic features—watercourses, mountains, roads and railroads—would appear on this first draft. Once the framework was drawn in, all the information that cavalry, scouts, interrogations and observations had accumulated was added to the skeleton map. This cumulative process gradually resulted in a military map. Sherman took these procedures so seriously that he delayed the forward movement of his armies for two days while awaiting the arrival of a copy of the U.S. Coast Survey’s excellent northern Georgia map so that its data could be added to an in-progress military map.

The mapmakers would prepare a grid on each of the maps to be copied and a corresponding grid on a blank piece of heavy drawing paper. The grids on the copied maps were adjusted so that the transferred data, as it was redrawn, was in the same scale as the new military map. The new map was embellished with delicate watercolors, and each color was keyed to various physical and cultural details: water, ultramarine blue; structures, black; woods, sap green; roads and railroads, red; and terrain features, sienna brown. The watercolors were not decorative. They provided clarity for commanders who often studied these maps under poor light and in extremely chaotic conditions. Sherman’s mapmakers used a standardized legend that synchronized the map symbols to ensure that a “Good Wagon Road” was not confused with a “Foot Path,” and that a “Marsh” was not mistaken for “Woods.”

Sherman’s topographical engineers also discovered the value of “land maps.” Northern Georgia had been surveyed and divided into numbered grids in the 1840s. Those numbers were shown on deeds, so Sherman could identify his headquarters, for example, as being located near “the northwest corner of lot 273.” With this effortless direction, he could easily and assuredly orient himself in the vast, sparsely settled wilderness through which his armies were maneuvering. As a final touch, it was the responsibility of anyone with a map to make corrections, add new information and return the corrected map to headquarters. Maps were thus constantly improving works-in-progress.

Having prepared a map, the next step was to get the map copied quickly and in sufficient numbers so that thousands of soldiers could coordinate operations and work in unison. Then and only then could a general’s plans bear any relation to what happened on the ground.

Sherman’s headquarters carried massive lithographic stones and presses and set them up to print maps wherever it was feasible. The presses made it possible to distribute excellent uniform copies on a need-to-know basis and to quickly make corrections and print new maps as soon as additional information became available. The maps could be printed on muslin, even on handkerchiefs for the convenience of cavalry. Uniformity was critical. It was far better for all the commands to have the same wrong map than for each of them to have different maps. It dramatically simplified orders: A corps could be ordered to march from the “D” in Dalton to the “V” in Dogwood Valley and to bivouac at the first or second “a” in Villanova.

The moment Sherman got his forces underway, it was clear that the Federals knew the topography of Georgia better than its Rebel defenders. A maneuver to flank his opponents by coming through Snake Creek Gap failed, but it was significant and telling that the Confederates were ignorant of the dangerous thoroughfare and had left it undefended. The maps that Sherman’s armies used were by no means perfect—but no other Civil War armies ever campaigned with better ones.

George Francis Robert Henderson, the eminent 19th-century British military historian, wrote in his biography of Jackson, “To handle an army in battle is much less difficult than to bring it on to the field in good condition.” Luck can always play an enormous role in the outcome of a single battle. A chance shot, darkness falling, a cloudburst, a misunderstood order: Any of these can, and sometimes did, make the difference between victory and defeat on the battlefield. Luck doesn’t have much to do with the outcome of a large army’s long march through vast stretches of wilderness in enemy territory, however. “Luck” in this situation consists of careful planning, proper logistics, willpower, nerves of steel and the finest possible maps.

It seems logical to conclude that by the end of the Civil War, the most successful generals in the field were the Union generals who had covered the most ground with the largest armies. They had marched hundreds of miles through enemy territory, defeated their opponents in battle, conquered and held territory, consolidated their gains and guarded their supply lines. They had refitted their armies and then marched again, continuously repeating the cycle against an adversary whose supply lines were shrinking and whose armies were consolidating. Without proper guidance, their task would have been virtually impossible. Military maps and topographical engineers played the role of prophets for the armies they served by preparing the way. Their maps are their testament.

 

For additional reading, see McElfresh’s Maps and Mapmakers of the Civil War and Make Me a Map of the Valley: The Civil War Journal of Stonewall Jackson’s Topographer, by Jedediah Hotchkiss and Archie P. McDonald.

Originally published in the June 2007 issue of Civil War Times. To subscribe, click here.  

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