Reflections on writing my Mercer Square blog

The Beginning

I’ve reached one hundred! No, not years, I’ve twenty more to go before I reach that esteemed age! I mean one hundred blogs. When I first started blogging in February of 2014, who knew I would still be at it ten years later! I have several folks I would like to acknowledge for their help to me along this journey:  John Hennessey, author and retired Chief Historian for the Fredericksburg and Spotsylvania National Military Park (FRSP), who challenged and encouraged me to begin to share my work via a blog. Also, Frank O’Reilly and Noel Harrison, both authors and National Park Historians at the FRSP. I frequently turned to them and their work for first rate information and inspiration. Another is my daughter, Megan Moore, a graphic designer who made helpful suggestions and guided corrections to maps and other graphic displays I created and used in my blog.

I chose to use Noel’s term of ‘Citizen Historian’ on my business card. I’m certainly not school trained in this regard. Rather than refighting the Battle of Fredericksburg, I looked for areas, or aspects of the battle or battlefield that intrigued me and dived down those rabbit holes and followed where they led.  

My business card, designed by my daughter.

Looking at topography is often where I start. The land with its accidents of terrain often influences what happens as individuals or armies move across it. For instance, the open plains found below Marye’s Heights outside Fredericksburg or in front of Prospect Hill appear to be simple level agricultural fields. Nothing could be further from the truth. To the infantry man ordered to cross those fields, any little dips, hollows, swales, ditches, depressions, etc., often meant the difference between life and death.

Finding the Swale

My writing all started because of a conversation with Peter Maugle, a then newly assigned FRSP Ranger. It was a cold wintry day in November 2011 at the Fredericksburg Visitor Center where I volunteer, and very few patrons came out that day to brave the cold. The conversation began with a discussion about how much protection the Union soldiers had in the Swale. I’d recently walked along the Sunken Road. Standing at the junction of Mercer Street adjacent to the Innis house, looking east, I noticed a distinct dip in the roadway just beyond Littlepage Street at 240 yards (220 meters). I could not see the lower portion of the wheels of a car parked there. If that was an indication of the famous swale, how long was it, or deep? My beginning point was looking for local maps from the Civil War. The 1867 Michler map was the place to start, or so I thought. The map technique of the day used splashes to indicate terrain, not contours.

As the Civil War was ending, the War Department decided that it needed to have a good set of maps to document where battles took place. For Fredericksburg this task fell to Major Nathan Michler, an engineer who was responsible for other surveys during the war. The resultant map, published in 1867, is frequently used, beginning with accounts by participants themselves of the Battle of Fredericksburg. This is a portion of that map centered on Mercer Square. Modern roads are overlaid on the right side by the City of Fredericksburg Graphics Department.

The first challenge I faced was what sort of topographic maps were available? The United States Geographic Service (USGS) had ten-foot contour maps, but this was too small a scale to really understand the dynamics of the swale. Then I found a printed five-foot contour map, better, but still not small enough to answer the question about the protection of Union troops in the Swale. I discovered that the City of Fredericksburg was using two-foot contour maps on its Graphic Information System (GIS). Now I had a reliable resource.

Mapping is always a challenge. These are positions of two topographic maps. On the left is from a United States Geographic Survey quad sheet for Fredericksburg. Its datum is ten-foot contours. On the right is from the City of Fredericksburg GIS system. It provides two-foot contour information. This is a portion of those maps centered on Mercer Square.

This is the same GIS map with houses removed. This makes it easier to see the two open plateaus which extend from above Mercer Street to below Wolfe Street. The tight contour lines between the two is the Swale. The scale is one-inch equals 250 feet with two-foot contour intervals.

Land Development

I was also fortunate that in the era in which Mercer Square was developed, starting in the early 1900’s, homes were placed on grade without large-scale reconfiguration of the building site. Lots were sold and developed individually. Each home was situated without major land changes. The GIS topographical mapping allowed me to “see” the whole of the area by stripping away the buildings. Interestingly, there are three utility or access alleys which run down at the back of the houses perpendicular to the Swale.  These unimproved corridors show how the original swale slope looked during the battle.

The Mercer Square portion of Fredericksburg was developed in the early 1900’s. Some of the earliest houses were built in 1905. These two Sanborn Fire Insurance maps from 1919 and 1927 display how quickly this development took place.
Mercer Square is bounded by Mercer Street to the north, Lafayette Boulevard to the south, Weedon Street to the east and Shepherd Street to the west. Internally Littlepage Street, Charlotte and Wolfe Streets which were used in my study. Importantly, there are alleys between the houses that align with Wolfe, Charlotte, and Mercer. The importance of these is they provide a good idea of what the slope of the Swale was in that location. The streets are graded to make travel less abrupt crossing the Swale thereby distorting the slope of the Swale.

Now I had the answer to the first half of Peter’s question; terrain. But what were the attributes of the rifled musket which the armies used in the Civil War? What were the flight characteristics of the Minie-ball ammunition used at the time? I’d read the report of the development of the US Model of 1855 small arms and ammunition which was signed by then Secretary of War, Jefferson Davis in 1856. From this document I understood the rationale behind the design of the Minie-ball, but not the parabolic flight path.

Rifle-musket ballistics

Somehow, I chanced upon an individual online who was able to provide the flight path information using a computer model. I provided the terrain data from the GIS map, estimating to the nearest foot by interpolating between contour lines along a given flight path. In the spring and summer of 2012, I generated detailed cross-sections that began at the stone wall along the Sunken Road. Once I had the flight path data, I was able to apply this to the cross sections. I provided my information to the FRSP staff, refining it based upon questions they asked and other discussions with them. To provide a better level of accuracy, I doubled the number of cross sections from those I used in my initial study. Having completed the impact of fire from the confederates, Frank O’Reilly asked me to look at the impact of Union fire from the Swale.

This cross-section is an example of those generated in my initial study of the Swale. I imagined a Confederate soldier stood at the stone wall sighting his rifle-musket out at the open field. The ground is noted by the green line. My question was how much protection would a Union soldier laying down in the Swale have? His line of sight is blue. The east-west bounds of Mercer Square are noted as the location of the Swale. I called the area of the Swale the zone of protection. The question was how much protection?

This cross section provides information about what could be seen by a confederate soldier and where he could aim.
This is limited by the top of slope of the Swale. It extends to the first point he sees land on the other or eastern side of the Swale. The area of defilade is the area within the Swale that could not be seen. I considered the body thickness or depth of a soldier laying down when I defined the beginning and end of the Safety Zone. The Minie-ball flew on a parabolic arc. When looking at where a bullet would strike, defined if a Union soldier could or could not be hit, even if he could not be seen. Those closest to the lip or western side of the Swale were safe. Some of the Union soldiers might be hit by a random bullet if he lay anywhere east of where a bullet could strike and the safety line (far). While he could not be seen, he could be randomly hit. In this cross section 40 yards and 55 yards (36 meters and 50 meters) respectively.

The result of this study showed that there was protection for Union soldiers sheltering in the Swale. They were crammed in side by side and lined up from the top of the Swale to the furthest extent. Most Union soldiers hiding in the Swale were out of sight of the Confederate infantry men. About half of those were also safe from the flight of the Minie-ball, while those furthest from the top of the slope were subject to random bullet strikes.

The result of my study is summarized graphically for the Swale in Mercer Square. The land leading up to and beyond the Swale was relatively flat with a slight rise on the way to the stone wall. The study is imprecise, influenced by the number of dead and wounded who occupied the ground which made new arrivals to the Swale struggle to get low to the ground. I estimate that roughly half of the Union soldiers seeking protection in the Swale were safe. The other half could be struck by a random bullet even though they could not be seen. Such are the vagaries of war. During the night following the battle, some Union units entrenched. Other units piled up the bodies of the dead to hide behind, gruesome but somewhat effective to survive.

Findings

The Swale at Mercer Square was a significant terrain feature in the Battle of Fredericksburg. It reduced the number of Union casualties by providing cover and concealment from fire by Confederates located behind the stone wall on the Sunken Road. Secondly, the width of the area in defilade, between where the line of sight touches the top of slope and therefore the number of troops that could take shelter in the Swale, has been undervalued by historians.

With encouragement from John Hennessey, I began posting my observations of the Swale. The outcome was blogs published between February and April 2014. I wrote five blogs on the Swale, two on the rifle musket and the Minie-ball, and one related to the impact of union fire from the Swale.  These are:

Finding the Swale – Feb 20, Modern Photographs of the Swale – Feb 26, The Swale in Cross-section – March 6, The Map Terrain – Mar 13, Muskets, and Rifle Muskets – March 26, Minie-ball, and its Parabolic Trajectory – March 27, Revising the Swale – April 3, Union Fire from the Swale April 10.

I maintained my interest in the Battle of Fredericksburg, spending the next six years investigating the area below Marye’s Heights. In the summer of 2020, I shifted my focus to the fighting at Prospect Hill, three miles to the south. This is where Union assaults broke through General Jackson’s line.

My next blog will start a study of logistics for both armies. I will begin looking at Falmouth train station. From time to time, I will share other reflections.

Sources.

Books.

O’Reilly, Francis Augustin, The Fredericksburg Campaign; Winter War on the Rappahannock, Louisiana State University Press, Baton Rouge, LA., 2003.

Harrison, Noel, Fredericksburg Civil War Sites, Volumes 1 and 2, E. Howard, Lynchburg, 1995.

Small Arms 1856 Reports of experiments with small arms for the military services, by officers of the Ordnance Department, U.S. Army (archive.org)

Internet

Ballistics Explorer. Ballistic Explorer – Oehler-Research

City of Fredericksburg GIS. Geographic Information System | Fredericksburg, VA – Official Website (fredericksburgva.gov)

Michler Map. Fredericksburg. [Dec. 1862] | Library of Congress (loc.gov) Sanborn Maps. Image 15 of Sanborn Fire Insurance Map from Fredericksburg, Independent Cities, Virginia. | Library of Congress (loc.gov)