The trench-eye view of Civil War tactics has evolved considerably over the past 25+ years. Most notably, the whole question of rifled muskets, engagement ranges, and training has received intense revision and renewed scrutiny—a debate which has added considerable depth to our understanding of how those weapons were used. No longer is it simply being taken for granted that just because a rifle-musket had a theoretical range of 600 – 800 yards, infantry units routinely fired at those ranges. Instead, we now know that the dance of death between attacker and defender was considerably closer, and more nuanced than was sometimes thought.
Far from ignoring the impact of the rifle, pre-war theoreticians instead thought they found a solution for an attacker: speed. In 1855, this solution was codified for American armies when U.S. Army Lieutenant William J. Hardee penned a new book of tactics. Hardee’s work, largely translated from the French and adapted for U.S. military regulations, was the first such revision in nearly twenty years, replacing Winfield Scott’s manual from the 1830s. Hardee’s manual sped up the pace of drill and combat dramatically, simplifying some regimental and company maneuvers to further increase swiftness under fire, all to help troops cross the expanded killing-ground of the rifle more rapidly.
Students of tactical history such as Paddy Griffith, Brent Nosworthy, and Earl Hess, among others, have given us interesting new insights into the nuances of Civil War tactics at the regimental level and below. That debate is far from over, but we have a sound basis for future discussion because of their work.
Tactics above the regimental level have been more neglected, however.
Hardee’s Tactics only replaced part of Scott’s work. Hardee addressed the “school” of the soldier, the squad, the company and the battalion (equivalent to a regiment) but stopped there. Scott’s ideas for the employment of multiple regiments in battle (in brigades and divisions only; Scott never envisioned a time when the U.S. Army would employ entire Corps) remained unchanged.
In 1862, not only did the U.S. Army’s senior officers find it troubling that their main tactical manual’s widely-known author was a prominent Rebel, but they also understood that the time had come to update the rest of Scott’s work. The man selected for this job was Major General Silas Casey. A West Pointer from the class of 1826, not only had Casey distinguished himself under fire in Mexico with Scott, but he had a long and respected peacetime career. He also led a division under McClellan on the Peninsula, where his command bore the brunt of the Confederate assault at Seven Pines. He was a highly qualified choice for this new task.
Late in 1862, Casey produced a three-volume work. The first two volumes drew heavily on Hardee—so much so that little really changed for company and regimental officers. The third volume, however, replaced Scott’s venerable manual and included some dramatic changes.
In Scott, the basic fighting formation for a brigade of four (or more) regiments was in a single line of battle. In theory, a full strength regiment numbered 1,000 men, and, when deployed in the shoulder-to-shoulder two rank formation called for by the tactics of the time, occupied a frontage of 250 yards. This density never changed, not in Scott’s, Hardee’s, nor even Casey’s Tactics; and the reason was simple. Given the weapons of the day, the only way to mass firepower was to mass men. Until the advent of magazine-fed weapons, that would not change. It did create problems for a brigade commander, however. If he placed those four regiments in a single line, he would be expected to control a formation one thousand yards (or more) in length. This feat would be difficult enough on a parade ground, let alone when complicated by the woods, crops, fences and hills of a real battlefield.
Of course, few regiments ever entered battle that strong. More typically, a regiment in battle might number 300-400 men, which corresponded to a frontage of 75 to 100 yards. Still, this left the brigade commander with a 400 yard frontage to manage under fire, often in timber. The situation was compounded at the divisional level when multiple brigades were deployed; leaving the divisional commander to manage a frontage of 800 to 1,200 yards, if not more. Union divisions were usually triangular in nature, but Confederate divisions usually incorporated four or even five brigades, meaning that in many cases a single Confederate divisional line of battle might stretch for as much as a mile. Consider the frontage of each of Stonewall Jackson’s divisions at Chancellorsville, for example; all formed with brigades abreast in heavy timber. It took Jackson a great deal of time to deploy, let alone manage a controlled advance in those circumstances.
These frontages, even if they were much shorter than the theoretical maximums called for in Scott, simply proved too difficult to handle under real-world conditions. Lines were slow in the advance, and more importantly, too slow to react to changing circumstances.
Of course, Scott’s tactics were intended for small armies, operating on limited battlefields. In 1837, no American soldier envisioned 60,000 or 90,000 men in a single army.
By the 1860s, now controlling forces larger than ever imagined by Scott, field commanders tinkered and adapted with different deployments for brigades and divisions, but they did so by trial and error. Casey’s work intended to codify those tinkerings into a new operational doctrine.
Casey’s solution was deceptively simple. Within each brigade, Casey favored a ‘square’ solution: two regiments leading and two behind, in support. The support line trailed at roughly 100 yards, depending on terrain. Brigade frontages were reduced to roughly 200 yards. The support line could move rapidly to extend that frontage, form a new line to defend a flank, replace a front line unit if needed, or provide a rallying force should the front line be driven back. A brigadier at the center of his brigade now needed to travel no more than 100 yards to reach any of his subordinate units. Fast, flexible, and effective.
Above brigade, Casey favored a formation that would be remain a part of U.S. Army doctrine for the next century or more. Summarized as “two up, one back” Casey envision a division moving with two brigades abreast, each with two regiments forward and two in support; and one brigade in reserve, centered behind the front. Again, the trailing brigade could move to the front or flank as needed, quickly.
These changes did have drawbacks. Initially, a division of twelve regiments would have no more than one third of its strength in the front line. Now two or three times as many troops might be needed to occupy the same width of frontage—troops that might not always be available. In practical terms, a Confederate brigade using the old system (Scott) would overlap a Union brigade formed using Casey’s tactics on both flanks. In theory, Casey’s system was flexible enough to extend those flanks as needed, matching the enemy man-for-man. However, a brigade commander not proficient in Casey’s system, or who was simply unable to effectively handle his command in the stress of combat, risked having one or more flanks turned—and nothing routed a Civil War formation more quickly than a turned flank.
Where sufficient friendly troops were available, where terrain limited such movements, or where competent brigade leadership was available, Casey’s was the superior system. But was new, and different. The War Department officially adopted Casey’s manual at the beginning of 1863, but it was not immediately embraced army-wide. In fact, the three main Federal armies—the Army of the Potomac, of the Cumberland, and of the Tennessee—each adopted the new tactics with widely differing enthusiasm. The progress of that adoption makes for an interesting study concerning the nature of institutional change and the influence of wartime leadership on the process.