How Hot Did Battles Feel For Civil War Soldiers?


Trendy meteorology saves lives. Throughout summer time months in humid climates, meteorologists fill our screens with forecasts for prime temperatures, rising dew factors, and excessive warmth indices. Corresponding warmth advisories from the Nationwide Climate Service warn of the life-threatening circumstances for many who fail to train discretion of their out of doors actions. To make sure our security, we’re cautioned to decelerate, hydrate, and keep indoors. However for many who fought within the Civil Warfare, there have been no such warnings, nor have been such discretions allowed to be the higher a part of valor. The latest discovery of sure primary-source climate knowledge, nevertheless, permits us to succeed in again in time and undertaking fashionable science on the human expertise of those that fought within the struggle.

Michael Jacobs taught
arithmetic, chemistry, and pure philosophy at Gettysburg Faculty. He lived from 1808 to 1871. (Gettysburg Faculty)

As a licensed battlefield information at Gettysburg, probably the most frequent questions I’m requested by guests is, “How scorching did it really feel to the troopers throughout Pickett’s Cost?” For many, that is an idle curiosity. However for historians, the query has all the time been, “have been the precise climate circumstances extreme sufficient to play a task within the final result of the cost?” Sadly, although we knew what the temperature was an hour earlier than the cost on July 3, 1863, we didn’t know what the measure of atmospheric moisture was, so we may by no means say with certainty what the climate felt like. And with out that key knowledge, we may by no means have interaction in a significant dialog concerning the climate’s potential influence on the climactic assault.

Climate commentary knowledge faithfully recorded through the battle by Pennsylvania Faculty’s Professor Michael Jacobs, who was doing so on behalf of the Smithsonian Establishment, indicated a excessive temperature of 87°F an hour earlier than the cost. Historians, nevertheless, have lengthy assumed that it should have felt a lot hotter. And with good motive, for within the mid-Atlantic area oppressive summertime “Bermuda” excessive strain programs sometimes prevail. However assumptions are one factor. The follow of historical past requires documentary proof. Sadly, the steadfast Jacobs was not within the behavior of recording measurements of atmospheric humidity, so his knowledge couldn’t be used to find out dew level, and in flip, warmth index. So, finish of story—proper? Not fairly.

Throughout Gettysburg’s 158th anniversary, this writer and meteorologist Jon Nese, Ph.D., revealed, for the primary time, a dependable estimate of what the dew level and ever-important warmth index measurements possible have been through the battle. These findings have been primarily based on evaluation of primary-source climate commentary knowledge recorded in Harrisburg, Pa., solely 35 miles from Gettysburg. Thankfully, in contrast to Gettysburg’s Professor Jacobs, the 2 climate observers in Harrisburg did report measurements of atmospheric humidity, known as “moist bulb temperature.” And it was these measurements that allowed for the first-ever scientifically primarily based estimate of humidity, dew level and in the end, warmth index—not solely at capital metropolis Harrisburg, however by extrapolation, at close by Gettysburg.

To make sure accuracy, our evaluation additionally factored in primary-source climate commentary knowledge from different close by areas, a reconstruction mannequin of climate maps from the interval utilizing a newly developed program created by the Nationwide Oceanic and Atmospheric Administration (NOAA), and a comparability of recent knowledge from Gettysburg and Harrisburg over a 30-year interval.

Taking all of this into consideration, our evaluation supplied some eye-popping outcomes—specifically a sturdy estimate indicating that at Gettysburg, on July 3, 1863, at 2 p.m., an hour earlier than Pickett’s Cost, the dew level measured a stifling 76°F and the warmth index measured a dangerous 98°F levels. And, in contemplating the truth that each day excessive temperatures usually happen later within the day (sometimes a number of levels increased), our estimations point out the warmth index on the time of the cost (3–4 p.m.) could have been as excessive as 105°F! With this, we now have a dependable estimate of how the climate felt to the troopers throughout Pickett’s Cost. In flip, historians lastly have the chance for a significant dialogue of how the climate could have affected the cost. However in the end, the advantages of our undertaking go far past Gettysburg.

As we have now seen, the power to establish dew level and warmth index stems from the efforts of varied mid–nineteenth century America climate observers, such because the aforementioned Harrisburg observers. And by the point the Civil Warfare had begun, an in depth community of climate commentary stations had been established on behalf of the Smithsonian (below the title of the Smithsonian Meteorological Venture). Within the early Sixties, the late climate historian David Ludlum was one of many first to make use of the Smithsonian’s information to investigate climate circumstances through the Battle of Gettysburg.

Extra not too long ago, historian Robert Okay. Krick’s 2007 landmark Civil Warfare Climate in Virginia used Smithsonian weather-observer information from Georgetown, D.C., to undertaking what the climate may need been in Virginia through the Civil Warfare. Krick correctly gave context to his knowledge by presenting quite a few firsthand accounts for any given month through the struggle with a purpose to give us what was, on the time, our greatest understanding of the climate in Virginia through the struggle.

This picture exhibits the unique Naval Observatory in its location within the Foggy Backside space of Washington, D.C. The observatory was there from 1844 to 1893. It was moved to a better location within the northeast portion of Washington, the place it nonetheless stands, however is closed to the general public. (Library of Congress)

Ken Noe’s The Howling Storm—Climate, Local weather, and the American Civil Warfare has contributed significantly to our general understanding of the impact of environmental circumstances through the struggle throughout all theaters of motion. However till now, no knowledge has been offered to point, with any diploma of certainty, what the dew level and warmth index circumstances may need been through the struggle apart from our latest undertaking highlighting the circumstances at Gettysburg. However now, by making use of our Gettysburg mannequin, we will analyze beforehand unused climate commentary knowledge from the interval to disclose dew level and warmth index circumstances elsewhere through the struggle. And the Virginia “theater of struggle” represents as soon as such location.

The “gold mine” supply that permits for the projection of dew level and warmth index measurements for Virginia comes within the type of weather-observation knowledge recorded in Washington, D.C., at a authorities location that was then recognized because the “Observatory, Washington Metropolis” (hereafter, the Observatory). The information utilized in Civil Warfare Climate in Virginia from Georgetown didn’t embody measurements of atmospheric moisture. These from the Observatory, nevertheless, did. And because of these measurements, correct figures for dew level and warmth index in Washington, D.C., may be decided for just about any date through the struggle for which circumstances and corresponding knowledge enable. Usually, warmth index measurements described as being within the “excessive warning” zone, or worse, may be computed just for cases when temperatures are above 80°F. And most frequently these circumstances happen throughout summer time and shoulder season months (i.e., Might and September).

It should be acknowledged right here that any measurement that’s projected for a given location in Virginia, say Cedar Mountain, primarily based on Washington knowledge (e.g., the Observatory), should be thought of along with the space between the 2 websites, elevation variations, and variations in sometimes prevailing climate patterns. Though an entire evaluation alongside these traces is past the scope of this text, a cursory have a look at two examples of the heat-related durations in Virginia, throughout which key actions occurred, clearly illustrates the potential advantages of a full evaluation.

Union troopers loiter within the shade on the Cedar Mountain battlefield in a photograph taken after the August 9, 1862, struggle. The blistering 109°F warmth index through the battle induced troopers to writhe in “painful contortions.” (Library of Congress)

August 5–12, 1862—Battle of Cedar Mountain. Robert Okay. Krick possible mentioned it finest in his Stonewall Jackson at Cedar Mountain, “That environmental elements have an effect on army affairs, generally decisively, is hardly a brand new thought. The wrestle at Cedar Mountain could be formed by terrain and floor cowl and different options, however none of those exceeded in significance the brutal fixed verity of the broiling solar.” To that highly effective assertion, we will now add the truth that our latest findings present definitive proof that the warmth at Cedar Mountain was far worse than both Krick or some other historians possible imagined.

Throughout this timeframe, information from the Observatory point out an eight-day interval of maximum warmth with each day warmth index measurements starting from a really uncomfortable 95°F to an especially harmful excessive of 109°F. Moreover, on seven of the eight days the warmth index measured over 100°F and on three of those seven days the warmth index both equaled or exceeded 106°F. In truth, in the future previous to the Battle of Cedar Mountain, the warmth index excessive on the Observatory measured 108°F.

Union troopers cool off in Virginia’s North Anna River. Photographer Timothy O’Sullivan took the picture on both Might 24 or Might 25, 1864, within the midst of the grueling Overland Marketing campaign. (Library of Congress)

Such a warmth index actually would have resulted in among the most dreadful circumstances to ever face Stonewall Jackson’s famed “Foot Cavalry” as they maneuvered August 7–8 to intercept Union forces previous to the Cedar Mountain combating. In doing so, they together with their adversaries endured warmth indices of 103°F and 108°F on August 7 and eight. After which, on August 9—the day of the battle—the warmth index reached its zenith. This was a day Krick aptly described as one in every of “broiling temperatures—the very best recorded on the day of battle for any main motion within the Virginia theater.” To wit, the Observatory air temperature on August 9 that fateful day measured 95°F (a number of ticks decrease than that listed by a Georgetown observer), however the atmospheric moisture measurement recorded there resulted in a outstanding dew level studying of 76°F and a warmth index of 109°F!

This data serves us effectively in validating accounts like that of the twenty seventh Indiana’s Edmund Brown, who supplied a firsthand account of the struggling attributable to the acute warmth index skilled by troopers who served at Cedar Mountain. As detailed in The Howling Storm, Brown indicated that because of the warmth, “We noticed many (troopers)…mendacity on the bottom, frothing on the mouth, rolling their eyeballs and writhing in painful contortions.”

Historians typically discover themselves doubting troopers’ accounts of the climate once they appear as if they is likely to be exaggerated. However the warmth index figures detailed right here greater than validate accounts corresponding to these of younger Brown. All of this should be thought of along with different elements impacting the troopers’ well-being, corresponding to the supply of water—or extra typically, the dearth thereof, fatigue from extended or troublesome marches and ongoing publicity to excessive circumstances. Add to this a magnified stage of discomfort on account of wool uniforms, cumbersome accoutrements, and cotton undergarments. Lastly, one should think about the influence of the solar’s penetrating rays. On August 9, it averaged largely clear skies in Washington and certain at Cedar Mountain as effectively. In truth, it is vitally essential to notice that warmth index measurements, or values, are for shady areas. In accordance with NOAA, publicity to direct daylight could enhance the warmth index values by as much as 15°F.

Southern cavalrymen taken prisoner through the June 17, 1863, Battle of Aldie. The estimated 118°F of that day would have taxed each man and horse. (Library of Congress)

One be aware of warning—recall that allowances should be thought of for the variations between validated Washington, D.C., Observatory measurements and projected circumstances within the neighborhood of Cedar Mountain. That mentioned, a cursory have a look at modern-day comparability knowledge from NOAA, between Washington and Warrenton, Va., 32 miles from Cedar Mountain, the closest obtainable fashionable “proxy,” for the month of August, considered over a 30-year interval (1990–2021), signifies very related common excessive temperature readings and common precipitation for these areas. Temperature-wise, although the common readings have been as much as 5 levels increased in Washington than Warrenton, this knowledge is sort of actually skewed by the “city warmth island impact” in modern-day Washington. City warmth islands didn’t exist in 1862. With this, a extra cheap variance, or margin of error, could be within the 1–2 diploma vary. Suffice it to say, August 5–12, 1862, was an especially scorching and humid interval in Washington and the encompassing areas, typified by harmful warmth index readings almost unprecedented through the Civil Warfare, together with Cedar Mountain and the neighborhood.

June 15–18, 1863—The Gettysburg Marketing campaign—Union and Accomplice forces on the march in Virginia, Second Battle of Winchester, and Battle of Aldie. If the climate at Cedar Mountain on August 9, 1862, felt like a broiling oven, the climate throughout an intense, albeit short-lived, blast of warmth in Virginia in June 1863 should have felt like hell on earth. Thankfully for the troopers of each side, the heavens granted fast reduction. However earlier than the warmth abated, among the most harmful circumstances recorded through the struggle fell upon each armies as they intently moved north towards their date with future at Gettysburg.

Information from the Observatory for this four-day interval reveal three days of maximum warmth with warmth index readings starting from 95°F to an alarming 118°F! Worse but, the day the Observatory warmth index measured a blistering 118°F (with the dew level at an unbelievable 80°F) was a day of devastating pressured marches for some and a day of fight for others, specifically these cavalrymen who noticed motion on the Battle of Aldie. And whereas the battling horse troopers clashed amid the staggering warmth and humidity, marching Accomplice and Union squaddies and artillerymen confronted life-threatening heat-related circumstances. Horses and mules would have been inclined to the acute warmth as effectively.

Troops of Maj. Gen. George Pickett’s Division crash into the U.S. line on the Copse of Bushes on July 3, 1863. Quite a few soldier accounts testify to the warmth they suffered via through the Gettysburg Marketing campaign. (Library of Congress)

Reinforcing all of this, a modern-day comparability between each Warrenton (as a Culpeper proxy) and Winchester, Va. (as in comparison with Washington) for the month of June (over a 30-year interval, 1991–2021), reveals very comparative local weather circumstances. This knowledge lends itself to the rivalry that in June 1863 the climate in Washington was possible similar to that skilled by the armies strung out between Culpeper and Winchester.

Whereas earlier accounts of temperatures within the 90s throughout this general timeframe lend credence to the quite a few firsthand accounts of struggling on account of excessive circumstances, the aforementioned heat-index figures provide new insights to the precise circumstances. Certainly, these figures provide an improved understanding of the primary-source accounts of struggling because of the warmth as detailed in extremely regarded sources corresponding to Edwin B. Coddington’s The Gettysburg Marketing campaign, Noah Andre Trudeau’s Gettysburg: A Testing of Braveness, and Stephen W. Sears’ Gettysburg. Examples embody that of the Sergeant Benjamin Hirst, 14th Connecticut infantry, who was a part of the Union military’s 2nd Corps pressured march on June 17: “We appeared to be suffocating at every step…robust males wilted as if blasted by one thing within the air.” That one thing was an estimated 118°F warmth index. And a member of the seventh Maine added: “It has been the toughest march in my expertise. It was scorching; the roads have been dusty and stuffed with trains and the boys fell out by the road-side in scores overcome by the warmth and exertion. Numbers died from sunstroke.”

However returning to Noe’s positive work, we discover probably the most descriptive accounts as conveyed by Sergeant Randolph Shotwell of the eighth Virginia Infantry, “Flesh and blood can’t maintain such warmth and fatigue as we have now undergone today. It’s horrible! All alongside the roadside since 9 o’clock this morning I’ve seen males dropping, gasping, dying—or already lifeless!” Shotwell continued, “…when one’s clothes is totally saturated with perspiration mixing with the mud in a dirty paste; and above all, weighs the heavy musket, the muffling blankets, gripping waist band and belt (upon which hold the heavy cartridge and cap bins) and the chafing canteen straps—is it unusual that one sees tons of of males gasping for breath, and lolling out their tongues like madmen?” By way of the magnitude of such fallout, one revealed supply signifies that in this timeframe, in James Longstreet’s Corps, as much as 500 males a day dropped out of the march, with some dying the place they fell.

Through the years, accounts like these detailed right here led historians to imagine the warmth was fairly excessive throughout this timeframe. And the climate commentary knowledge from the Georgetown observer, as detailed in Krick’s Civil Warfare Climate in Virginia, appeared to buttress these conclusions. But there was all the time a level of uncertainty with regard to the precise circumstances.


In diaries and letters, and in memoirs written lengthy after the struggle, troopers remembered warmth as an enemy that attacked each side. In the course of the march to Gettysburg on the Baltimore Pike on July 1, 1863, a day of average temperature however excessive humidity, the solar beat down on twelfth Corps troopers. “It was a scorching day,” recalled a member of Colonel Charles Sweet’s brigade, “The solar was scorching. The bottom was scorching, and the boys panted like canines on the chase and sweat and sweltered via clouds of mud that got here from Knapp’s Battery in our entrance.” 

Ernest Wait of the nineteenth Massachusetts wrote of 1 exhausting slog, “The solar was now effectively up and the air intensely scorching, inflicting the persperation to expire and, operating down the face, drip from the nostril and chin. The salty liquid acquired into the eyes, inflicting them to burn and good and it ran down from below the cap, via the mud and down the perimeters of the face which was quickly coated with muddy streaks, the results of repeated wipings on the sleeves of the shirt.” And 1st Tennessee personal Marcus Toney frankly admitted in his aptly named memoir, Privations of a Non-public, “what number of wiggletails and tadpoles I’ve drunk won’t ever be recognized,” so determined did the broiling solar make him for a drink of water.


Thankfully, our latest discovery of climate commentary information from the Observatory in Washington enable for a dependable science-based estimation of the dew level and warmth index within the aforementioned areas in Virginia through the detailed durations of time. Furthermore, this data not solely corroborates the beforehand detailed accounts however provides a brand new certitude to the understanding of the influence these horrific circumstances had on the unlucky troopers who skilled the identical. In abstract, we knew the armies in Virginia, throughout these time frames, had suffered below extreme warmth, however now we all know it felt a lot hotter than we ever dared think about.

Thus, the newly found knowledge and the Gettysburg “mannequin” enable for evaluation of those examples in addition to different cases of maximum warmth in Virginia through the Civil Warfare. As well as, primary-source climate commentary knowledge is on the market for different areas adjoining to campaigns and battles within the border states. With this, there may be nice potential for an elevated stage of understanding with regard to the troopers’ affected by excessive warmth and corresponding penalties in related actions through the struggle—not solely in Virginia however in different theaters of motion as effectively. And conversely, this knowledge may also be used to contradict accounts of oppressive warmth when the precise circumstances weren’t too drastic. One such instance was the First Battle of Manassas. However that’s one other story, for an additional day.

Jeffrey J. Harding’s profession as a Licensed Battlefield Information at Gettysburg spans 22 years. Jeff can also be the writer of the not too long ago launched and extremely acclaimed guide, Gettysburg’s Misplaced Love Story—The Sick-Fated Romance of Normal John Reynolds and Kate Hewitt. He want to acknowledge meteorologist Jon Nese, Ph.D., and retired Nationwide Park Service scholar John Hennessy for his or her help in getting ready this text.

this text first appeared in civil struggle instances journal

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