Review - "The Weather Gods Curse the Gettysburg Campaign" by Nese & Harding

[The Weather Gods Curse the Gettysburg Campaign by John M. Nese & Jeffrey J. Harding (Arcadia Publishing and The History Press, 2025). Softcover, maps, photos, illustrations, tables, charts, appendix. 238 Pp. ISBN:978-1-4671-5846-6. $24.99]

Every Gettysburg student is familiar with the gist of the campaign's weather story. In summary, the combatants had to endure early-summer high heat and humidity during forced marches and fighting, and the post-battle retreat and pursuit offered the survivors different miseries to deal with in the form of rain and mud. However, one might reasonably ask how much deeper we can take this broad-stroke weather assessment of the campaign. Is a daily, perhaps even more granular, description and analysis of weather's impact on men and operations before, during, and after the July 1-3 Battle of Gettysburg possible? According to John Nese and Jeffrey Harding, the answer to that question is a resounding 'yes,' and all is revealed in their fascinating book The Weather Gods Curse the Gettysburg Campaign.

Nese, an academic at Penn State's Department of Meteorology and Atmospheric Science, and Harding, a licensed GNMP battlefield guide, draw upon their respective areas of expertise (in weather science and Gettysburg military history) for a fresh examination of this underexplored topic. The book begins with a meteorological science primer that, among other things, provides background information necessary for readers to understand the practical meaning and significance of a variety of weather-related measurements that the authors utilize in their analysis, from simple thermometer and dewpoint readings to more complex heat index and wet-bulb globe temperature calculations.

Very significant to the study is its employment of a relatively new computer model developed by the NOAA that allows its users to recreate weather maps of the past, keeping in mind that its reliability is more macro than micro. This "reanalysis system" represents one among many research tools that Nese and Harding have at their disposal, the integration of which offers keen insights into the weather encountered by Union and Confederate soldiers in Virginia, Maryland, and Pennsylvania during June and July 1863.

Underpinning Nese and Harding's research is a critical body of recorded observations from contemporary weather watchers such as the government staff of the Naval Observatory, the network of daily weather reports from military installations across the country, and dedicated civilian recorders such as those who submitted their data to the Smithsonian Meteorological Project. Many of the individuals involved are profiled in the text. This data recorded from both near and afar, combined with Nese's expert knowledge of local and regional atmospheric and weather patterns, allows the study to trace reliable meteorological readings at any point in time across the campaign's multi-state path. 

It is often said that if you want to know the weather just look out your window, and the historical equivalent of that window view is represented by the approximately 1,500 soldier and civilian journal and letter accounts of the weather that the authors have recovered and organized for their research. This collection of subjective firsthand perspectives critically augments Nese and Harding's quantitative analysis, and the most salient portions of select passages are interspersed throughout the text. In an ingenious manner, Nese and Harding combine this historical documentation with the aforementioned modern weather modeling techniques to provide us with a remarkably detailed reconstruction of weather effects during the entire run of the campaign. Additionally, findings and descriptions revealed in the narrative are supplemented by a plethora of historical and modern weather maps, charts, and tables. For easy reference, a record of daily weather data and notes for the period June 3 to July 14 is also compiled in tabular format in the appendix.

As explained in the book, the June 10-18 heatwave experienced by the armies in the field was exceptional for late spring. Unfortunately for the health of those involved, it also coincided with a period requiring hard marches that resulted in widely reported physical debility and heatstroke death (although those numbers are not quantified). Data suggests that the severity of the conditions was historically rare for June, marking that heat wave as one among several of the campaign's exceptional weather-related events. Without the ability to forecast weather, generals lacked the information needed for weather-adjusted planning (where possible). Examples cited in the book of forced marching during heat wave conditions and operational pauses during fine marching weather are signal reminders of one of many chance elements that contribute to the overall friction involved with conducting war. In an interesting side note, the authors mention that the mixed-material jean cloth of Confederate uniforms breathed better than the wool jackets issued to Union troops. That, combined with the lighter color, made the southern shell jackets more comfortable in hot summer months for those wearing them. Indeed, while today's writers often emphasize the presumed general discomfort of Civil War uniforms, the soldiers themselves complained vastly more about their feet and footwear problems during long, hot marches.

For the three-day battle itself, thermometer temperatures weren't considered extreme on the first day, with much of the discomfort coming from the humidity. July 2 was much hotter, and the book effectively uses the very lengthy approaches to the battlefield of Law's Brigade on the Confederate side and the Union Sixth Corps as case studies of the day's weather effects on marching and fighting. Even though the recorded shade temperature still may not have been extreme, the heat index likely pushed 90 degrees and the effects of direct sunlight made the forced marching even less bearable. In contrast to Sixth Corps, whose march was marked by periodic rest and hydration breaks, Law's Brigade had little of either. The weather, lack of recovery time, and rugged terrain at Little Round Top all hindered the brigade's chances for sustained success as it spearheaded the attack during one of the three-day battle's key moments. The enervated condition of Law's men upon arrival at the front likely contributed mightily to the large prisoner haul that the formation lost during the celebrated Union counterattack involving the 20th Maine. The data and NOAA modeling employed by Nese and Harding confirms contemporary observations that July 3 was the worst of the three in terms of physical discomfort. With the heat index almost certainly over 100 degrees (with some likelihood of even reaching 105), and keeping in mind that the index relies on shade measurements, such brutal body-stressing conditions undoubtedly impaired fighting endurance and performance during Pickett's Charge, especially for the attacking troops.

As detailed in the literature, from July 4 onward the principal weather challenge switched over from head and humidity to rain, with thick mud and rising streams hampering both Confederate retreat and Union pursuit. The volume's data gathering and analysis adds a great deal in the way of finer detail when it comes to the likely timing and quantification of the rainfall episodes. Nese's applied expertise shines through the entire book, but one of the finest examples of it is shown in the attempt to understand the deluge that preceded the Potomac River recrossing of Lee's army back to Virginia. Gaps in the instrument readings and lack of expected results from the NOAA reanalysis model hinder explanation of the massive river rise, but Nese is able to provide a solid meteorological basis for the event through a more complex interpretation of regional weather patterns utilizing contemporary data gathered from afar. On a final note, findings confirm that the steep rise of the Potomac behind Lee's army at Williamsport was a truly extraordinary weather event for any July in recorded history. Lee's army could count itself fortunate to have escaped.

John Nese and Jeffrey Harding's The Weather Gods Curse the Gettysburg Campaign is a truly remarkable, highly useful, and completely original contribution to the ongoing study of the Gettysburg campaign and battle. As the authors maintain, weather and its extremes affected how the campaign unfolded at every stage of its development, and it was a testament to the human endurance and ingenuity displayed by the armies that weather-induced disaster was avoided. Accessible to general reader and specialist alike, this masterfully conceived and executed study is an essential addition to the Gettysburg library, a key reference for every future chronicler of the campaign.