Cedar Mountain to Antietam: A Civil War Campaign History of the Union XII Corps, July-September 1862 Review

cedar mountain to antietam

By M Chris Bryan
El Dorado Hills, CA: Savas Beatie, 2022
ISBN 978-1-61121-577-9
Photographs. Maps. Appendices. Notes. Bibliography. Index. Pp. xi, 393. $34.95

Of the tens of thousands of books written about the Civil War since 1865, a relative handful have been written from the perspective of one of the core elements of army organizations—the corps. While soldiers usually identified with their regiments—understandably so with the regiment being formed around friends, family, and neighbors from their localities—it was through corps in which they conducted their operations and by which they were organized and identified, with distinctive insignia by 1863 in the case of the Army of the Potomac. Only recently have corps-level histories begun to be woven into the historiography, filling an obvious void in understanding the ebb and flow of battles and the intricacies and intrigues of commanding ten thousand men across the battlespace.

In fact, most of the major corps-level histories are from over a century ago and are in dire need of a refreshed look. Fortunately, publisher Savas Beatie has been leading the way, first with a two-volume set on the Union’s XI Corps, and now M. Chris Bryan’s fine work on the XII Corps in Cedar Mountain to Antietam. 

Importantly, Bryan sets out to give readers more than a tactical-level study of a corps on campaign; he endeavors to “tell the story of the soldiers of the XII Corps” as “the efforts of the…Corps does not figure prominently in the literature” (p. xi) of the Antietam Campaign, including the official records, according to one of the battle’s main historians, Ezra Carman, himself a veteran of XII Corps. XII Corps may not have the brand-name recognition of other corps of the Army of the Potomac, but in Cedar Mountain to Antietam, Bryan does an admirable job telling the story and recognizing the efforts of the 7,000 men of XII Corps, bringing their experiences and trials to life.

Bryan’s account begins not with XII Corps, but with a small two-division organization under Brigadier General Nathaniel Banks conducting operations in the Department of the Shenandoah, largely operating against Major General Stonewall Jackson’s forces protecting the Valley. Briefly touching on the 1862 Valley Campaign, Bryan discusses Banks’s divisions being consolidated into the II Corps of the new Army of Virginia under Major General John Pope. Bryan spends the next five chapters stepping through a roughly six-week period of the corps’ operations against Jackson at Cedar Mountain and the disaster at Second Manassas, as the war moved inexorably toward one of the most consequential battles on U.S. soil to that point.

The subsequent six chapters delve into the corps’ actions on the morning of the Civil War’s single bloodiest day along Antietam Creek outside the town of Sharpsburg, Maryland. Nearly 100 pages over three chapters capture XII Corps’ actions in roughly one-hour increments. This gives enough depth to the fight without bogging readers down in too much detail while engaging the “voices” of the soldiers and giving the narrative additional gravitas. Appropriately, Bryan also balances his narrative with Confederate perspectives, allowing readers to gain a full understanding of the ebb and flow of battle, as well as their reactions to the same fights.

Bryan’s impressive research and compelling narrative do great credit to the officers and men of XII Corps, bringing their history to the fore through their own voices, struggles, and sacrifices. By keying into a few brief months of the corps’ existence, Bryan is able to focus his narrative across several key 1862 campaigns without overwhelming readers. Well-illustrated with photographs and twenty-eight excellent maps by cartographer Hal Jespersen, Bryan brings XII Corps to life in an accessible and understandable way. Cedar Mountain to Antietam bridges the gap between the popular regimental micro-histories and the larger battle or campaign-level narratives.

Lieutenant Colonel Paul H. Whitmore, USSF
King George, Virginia