Author Interview--Scott Hippensteel (Sand, Science, and the Civil War) Part 2

Hello H-CivWar Readers:

Today we continue our conversation with Scott Hippensteel to talk about his new book, Sand, Science, and the Civil War: Sedimentary Geology and Combat, published by University of Georgia Press in March 2023.

Part 1

I am glad you received so many helpful comments and it shows in the book's accessibility. Let’s turn to the book, you have lots of science in the book and I would assume most of the officers, and especially soldiers, did not have a solid background in geology, correct? In how much did officers take soil into consideration for battles, routes, or winter camps and how much was just coincidental or prudent use?

SH: Most of the soldiers and officers didn’t have any basic understanding of geology, in large part because it was a brand new science in the 1860s. I drew a connection between the most influential American military scholar prior to the war, Denis Hart Mahan, and the most important geologist, Charles Lyell.  Both published their first important textbook within a few years of each other in the late 1830s.  As a result, the officers educated prior to the outbreak of fighting would have taken courses in topography and engineering, but with no connection to geology.
The field commander who most likely had the best understanding of sedimentary geology at the beginning of the war was Union general William Rosecrans.  Before the war he spent some time studying minerals and rocks, but today you’d consider him a hobbyist or, at best, an amateur geologist.  I’ve always thought, from a geological perspective, that it was a shame that George “The Rock of Chickamauga” Thomas never got to face off against Stonewall Jackson in a major battle.

As far as the officers’ consideration of soil with respect to battles, routes of travel, or winter camps, the answer is more complicated.  For battles, there is clear evidence that they were more concerned with topography (high ground) than soil thickness.  As a result, many great defensive stands were made on slightly higher ground that was absent of trenches or field fortification.  Some of the best terrain at Gettysburg and Stones River, for example, had the thinnest soil.

With respect to marches and road conditions, I went into some detail discussing what, geologically, makes a road impassable or causes it to deteriorate quickly.  I don’t think the officers and logisticians at the time would have been concerned with whether the clay was cohesive or adhesive, only whether the men could march across it and the wagons could get through.  The result was often a rapid decline of the road conditions and fiascos like Burnside's infamous Mud March.

One area where geology influenced tactics that hasn’t been widely discussed also deals with the finest of sedimentary particles.  Add water to clay and silt and you get a muddy mess.  Dry the same material completely, send tens of thousands of men stomping across it, and you get an unbearable dust storm.  Consider how the slightly damp ground kept the dust down for Jackson’s surprise flanking march at Chancellorsville compared with, only a month later, how dust betrayed Longstreet’s march in front of the Union left at Gettysburg.  Interestingly, soldiers’ diaries contain a similar number of (justifiable) complaints about this tiny sediment, regardless of whether it was too wet or completely dry.

You have a significant portion of the book devoted to sand—what makes sand such a fascinating and important tool in war? Similarly, how did that understanding of the useful properties of sand grow in the course of the war?

SH: Sand is abundant, reusable, very hard, easily excavated and moved, and found on all battlegrounds.  I summarized how sand was important for battlefields from all different physiographic environments, because the influence differed depending on the geographic location of the battlefields and local geology.  Just to give you an example, here is a (summarized) list of more than a dozen ways sand provided a defensive advantage for coastal fortifications:

Sand is so abundant and easy to excavate and reshape that massive fortification can be constructed almost overnight.  Sand is also reusable:  the sand excavated from a moat or ditch can be used to construct a parapet or glacis.  Sand deflects projectiles and diminishes the effects of explosions and the sediment eliminates ricocheting fire within embrasures, especially with small-arms fire.  And sand, when hit with a heavy artillery shell, will not splinter or fracture, creating the type of deadly secondary projectiles associated with hard rock or brick.   Most fine sediments will often fall back into place after being hit by artillery shells, so a structure needs little repair.  The result makes a sand parapet especially difficult to reduce.   

Friction between sand grains limits penetration of solid shot.  This inter-grain friction is also important when siting artillery, as sand can support a great amount of weight compared to other materials.  Sandbags are easy to make and move and, most importantly, bulletproof.  (What other modern battlefield implement do we have that has survived so unchanged since the Civil War?)  Sand is also incredibly abundant adjacent to the oceans and, for coastal artillery positions, it is especially useful:  pile it high to create plunging fire, excavate to sea-level and create ricocheting fire across the water. 

Sand structures can also be modified quickly after a fortification is constructed.  Many coastal fortifications were reconfigured multiple times during the war to gain advantage – try that with a brick fort.  Sand is difficult for attackers to walk over and fatiguing to run over. During several Federal assaults along the beaches, the soldiers were exhausted long before they reached the enemy’s position.  Clean, mature sand is also porous and permeable. It drains easily, and, if saturated, sand is permeable enough to be a great source of drinking water.  Finally, sand isn’t flammable.  I apologize if this answer is too granular.

To answer the second part of your question:  The understanding of all of these properties absolutely did evolve during the war.  This is easy to document by looking at the official reports and letters produced by Quincy Gillmore.  After the fighting on Morris Island, his correspondence rings of astonishment at how useless his artillery was when firing into sandy fortifications.  The effects of his guns were “astonishingly slight” and the penetration of the massive shells “trifling”.  The results of his great bombardment was “by no means commensurate with the expedition of ammunition involved”.  The Union army went so far as to set up informal penetration tests of the Morris Island sand, firing a variety of carbine and rifle bullets into different varieties of “siege material” to determine the comparative strength of the sand.  By 1865 Gillmore had repeatedly made clear his observations of the value of sand, over any other material available for temporary fortification:  “Against the destructive effects of projectiles, pure quartz sand, judiciously disposed, comports itself unlike any other substance, and for certain parts of fortifications its particular properties suggest its exclusive use, in preference to ordinary earth.”

As we wind down the interview, I want to switch gears pretty dramatically. The last part of your book was extremely intriguing as you dealt with long-term lessons and preservation efforts. How much did military planners learn from the Civil War?

SH: A great deal, especially with respect to coastal fortifications.  After the Civil War, in response to the threat of larger, faster, steam-powered ships with substantially heavier armament, many European countries began to explore new means of using iron in defensive works.  In the United States the economic impact of the war prohibited such an expensive defensive upgrade, so instead we chose to stick with sand.  Even in the age of concrete, sand still reigned supreme, as demonstrated by Col. Eden Wilson’s Notes on Seacoast Fortification Construction (1920):  “The same amount of protection could be obtained at less cost with a comparatively thin concrete wall, having sand in front of it, than if concrete was used throughout.”  During the Endicott Era of massive reinforced concrete bunkers and disappearing guns, sand remained a critical component.  Sand was piled to bury, protect, and camouflage many of the giant coastal batteries and on most islands the only place such a heavy structure could be constructed without sinking was in the sand dunes.

In the final chapter of the book I walk through each of the post-Civil War conflicts that involved the United States and discuss how the understanding of the importance of sand and sediments increased through time.  Some of the stories are especially interesting:  Few people know that only two men landed on the beaches of Normandy twice in the spring of 1944, and both had special training in sedimentary geology.  Their first covert landing was to collect sand samples to make certain the beaches had the strength to support tanks, then they later joined the amphibious assault.  Other stories are more controversial, such as during the Gulf War, when the US First Infantry Division (Armored) faced the Saddam Line, a compound series of defensive trenches cut into the deep sand.  The Americans simply used tanks and earthmovers to bury their enemy alive.  Sand was no longer just a defensive force multiplier, it had become an exceedingly efficient offensive weapon.

Related to the previous questions, today we for example have the remains of Fort Sumter but not Fort Fisher or Battery Wagner—could we have and should we have saved either of the latter two? How does having the masonry forts but not the sand one impact the public perspective of the Civil War?  

The preservation of temporary coastal fortifications is another controversial topic.  I fully support all battleground preservation efforts, and am a member of the American Battlefield Trust.  However, most conservation efforts on the mainland do not cause destruction of land elsewhere.  At Fort Fisher, for example, the granite revetment that has temporarily preserved the fraction of the fort that survives today will undoubtedly cause more erosion along other portions of the shoreline.  

There is usually a trade-off along the coast when it comes to preservation efforts.  Had we been able to preserve Battery Wagner on Morris Island, it would have prohibited construction of the Charleston Harbor jetties and Folly and Kiawah Islands, to the south, would have suffered even more shoreline erosion.  Instead, we lost Battery Wagner, but that same sand was diverted offshore by the jetties, where it helped to bury, protect, and preserve the Confederate submarine H.L. Hunley.    

The second half of your question, about having masonry forts and not temporary fortifications and public perspective of the Civil War, is especially interesting and something that hasn’t been explored in depth before.  Certainly the survival of these Third System fortifications increased their reputation as being robust and important defensive sites, even if they were obsolete by the start of the war.  However, this vulnerability is easily observed when viewing the single remaining tier of Fort Sumter or the unrepaired shell scars in the brick at Fort Pulaski.  We are fortunate that the coastal engineers who selected the sites for these massive brick fortifications chose, for the most part, locations along the coastline that are fairly stable and have been more resistant to shoreline erosion and hurricane damage than most.  Nevertheless, the next twenty years of sea-level rise and shoreline retreat are going to intensify the challenges for preserving these remarkable brick citadels along the Atlantic and Gulf coasts. 

You already have done three books on the Civil War, do you have plans for a fourth or is another war drawing your interest?

SH: My father was born on June 6, 1944, so growing up we always had a copy of Cornelius Ryan’s The Longest Day lying around.  How could a coastal geologist, who is interested in military history, not be fascinated by Pointe du Hoc or the sandy bluffs overlooking Omaha Beach?

I have one more book proposal under consideration for a project that uses science to interpret the “combat” photographs from the Civil War, but then I’m going to focus my studies on how geology influenced coastal operations from the American Revolution to the present day.  I’m especially interested in how sedimentary geology affected the amphibious assaults from World War II and Korea.  The beaches along the Atlantic, Mediterranean, and Pacific are so geologically different and their influences on the tactics and fighting were equally as important as that of sedimentary geology during the Civil War.