The infantry in the American Civil War comprised foot-soldiers who fought primarily with small arms and carried the brunt of the fighting on battlefields across the United States. The vast majority of soldiers on both sides of the Civil War fought as infantry and were overwhelmingly volunteers who joined and fought for a variety of reasons. Early in the war, there was great variety in how infantry units were organized and equipped - many copied famous European formations such as the Zouaves - but as time progressed there was more uniformity in their arms and their equipment.
Historians have debated whether the evolution of infantry tactics between 1861 and 1865 marked a seminal point in the evolution of warfare. The conventional narrative is that officers adhered stubbornly to the tactics of the Napoleonic Wars, in which armies employed linear formations and favored open fields over the usage of cover. However, the greater accuracy and range of the rifle musket rendered these tactics obsolete. The result was greater casualties and increasing usage of trench warfare, presaging the course of future conflicts. More recent scholarship has challenged this viewpoint and argued the impact of the rifled musket was minimal. In this interpretation, the tactics used remained practical and the decisiveness of battles was affected by other factors.
This debate has implications not only for the nature of the soldier's experience, but also for the broader question of the Civil War's relative modernity. Williamson Murray and Wayne Wei-Siang Hsieh argue that the conflict was resulted from "the combination...of the Industrial Revolution and French Revolution [which] allowed the opposing sides to mobilize immense numbers of soldiers while projecting military power over great distances."
Outbreak of war At the start of the war, the entire United States Army consisted of 16,367 men of all branches, with infantry representing the vast majority of this total. Some of these infantrymen had seen considerable combat experience in the Mexican–American War, as well as in the West in various encounters, including the Utah War and several campaigns against Indians. However, the majority spent their time on garrison or fatigue duty. In general, the majority of the infantry officers were graduates of military schools such as the United States Military Academy.
In some cases, individual states, such as New York, had previously organized formal militia infantry regiments, originally to fight Indians in many cases, but by 1861, they existed mostly for social camaraderie and parades. These organizations were more prevalent in the South, where hundreds of small local militia companies existed to protect against slave insurrections.
With the secession of eleven Southern states by early 1861 following the election of President Abraham Lincoln, tens of thousands of Southern men flocked to hastily organized companies, which were soon formed into regiments, brigades, and small armies, forming the genesis of the Confederate States Army (CSA). Lincoln responded by issuing a call for 75,000 volunteers, and later even more, to put down the rebellion, and the Northern states responded. The resulting forces came to be known as the Volunteer Army versus the professional Regular Army. More than seventeen hundred state volunteer regiments were raised for the Union Army throughout the war. In all, approximately 80% of Union soldiers fought as infantry, while 75% of Confederate soldiers were infantry.Guelzo, A. C. (2012). Fateful Lightning: A New History of the Civil War and Reconstruction. Italy. Oxford University Press, USA. p. 249-250
Organization
The regiment was the foundational unit for mustering, training and maneuvering infantry during the Civil War.Eicher, p. 65 The typical infantry regiment nominally consisted of about 1,000 soldiers organized into ten companies. It was commanded by a colonel (assisted by a lieutenant colonel and at least one major), with a dedicated headquarters and a band of musicians (the band later removed).Griffith, 91-93 Regiments were designated by a number and the name of the state that raised them, such as the 10th New York or 48th Mississippi.Coggins, J. (2012). Arms and Equipment of the Civil War. United States: Dover Publications. p. 21-22 Each regiment also had their regimental colors, flags which not only served to denote position and alignment on the battlefield but which held special emotional significance. To be chosen as the color guard charged with protecting these flags was a special honor, and one of the most dangerous positions in the regiment.Barney, W. L. (2011). The Oxford Encyclopedia of the Civil War. Spain: Oxford University Press, USA. p. 127
The actual authorized strength for a regiment could vary greatly. Within the Union Army there were three different regimental models: pre-war Regular Army regiments had an authorized strength of 878 soldiers; new Regular Army regiments created for the war were authorized up to 2,452 soldiers; and regiments raised by the states for the Volunteers Army ranged from 866 to 1,046. The Confederate States Army had their infantry regiments fixed to a maximum strength of 1,045, but they also experimented with forming legions, large regiments that combined infantry with cavalry and artillery. The concept was abandoned soon after the war began however for being too unwieldy.Gudmens, J. J. (2005). Staff Ride Handbook for the Battle of Shiloh, 6-7 April 1862. United States: Combat Studies Institute Press. p. 4-6
The official structure for regiments was not always followed: the 66th Georgia for example constituted 1,500 soldiers organized into thirteen companies at its formation, while the 14th Indiana was formed with 1,134 men. Nor did regiments stay at full strength. After just six months of duty, a regiment which started with 1,000 men often could muster only 600 or 700 on account of desertions, illness, detachment on special duty, and other factors. On average the fighting strength of a Civil War regiment was just 400 soldiers, with Union regiments having slightly more and Confederate regiments slightly less. Ironically, the smaller size of regiments had the unintended effect of making them more maneuverable and easier to command on the battlefield.
The eventual fate of many regiments was to continue losing soldiers until they were deemed combat ineffective and either consolidated or disbanded. Both armies made attempts to replenish regiments back to their full strength, but the process was haphazard and infrequent; nor was it helped by governors who preferred to meet their quotas by creating new regiments as a form of patronage. On the whole though, the Confederates put more effort into funneling replacements into existing regiments.Griffith, p. 94-96
Below the regiment was the battalion, although with few exceptions there was no formal structure, only that any two or more companies constituted a battalion. If a regiment was formed with only eight or fewer companies, it was referred to as a battalion. The company was traditionally seen as the smallest military unit and often recruited from a local community.Eicher, p. 66 Its authorized strength was approximately 100 soldiers, led by a captain who was assisted by a couple of lieutenants and several non-commissioned officers (NCOs). However, as with regiments the actual strength of a company was often reduced to half or less.Axelrod, A. (2017). Armies South, Armies North. United States: Lyons Press. p. 69-71 A company could further split into two platoons, with each divided into two sections of two squads each. The smallest sub-unit were "comrades in battle" or the four men adjacent to each other in the line of battle. Such small units rarely featured in Civil War combat with some exceptions, such as during skirmishing.Hess, E. J. (2015). Civil War Infantry Tactics: Training, Combat, and Small-Unit Effectiveness. United States: LSU Press. p. 40
unit number+Confederate ArmyStaff Ride Handbook for the Battle of Perryville, 8 October 1862. (2005). Fort Leavenworth, KS: Combat Studies Institute, US Army Command and General Staff College. p. 5 regiments 642 legions 9 battalions (separate) 163 companies (separate) 62
unit number+Union Army regiments (Regular Army) 19 regiments (Volunteer Army) 2,125 battalions (separate) 60 companies (separate) 351
Individual regiments (usually three to five, although the number varied) were organized and grouped into a larger body known as a brigade. A brigade was supposed to be commanded by a brigadier general, but it was often the case that the senior-most colonel would lead the unit. Confederate brigades usually combined regiments all from one state while Union brigades would mix regiments from different states. Two or more brigades were combined into a division, usually commanded by a major general, with several divisions constituting a corps and multiple corps together making up an army.Axelrod (2017), p. 63 In the beginning infantry divisions typically had cavalry and artillery units attached to them, although as the war progressed these were spun off into their own units under corps and army control. Union divisions were numbered based on their position within their corps, as were brigades within divisions. The same was true with Union corps at first, but they eventually came to be numbered irrespective of their army. For the Confederates corps were numbered within their respective armies, but divisions and brigades were identified by their commanding officer.Wilson, J. B. (1998). Maneuver and Firepower: The Evolution of Divisions and Separate Brigades. United States: Center of Military History, U.S. Army. p. 13-16 Confederate corps and armies were commanded by a lieutenant general and full general respectively, while major generals commanded both in Union forces.
unit type low high average most frequent+Confederate ArmyEicher, p. 73. corps per army 1 4 2.74 2 divisions per corps 2 7 3.10 3 brigades per division 2 7 3.62 4 regiments per brigade 2 20 4.71 5
unit type low high average most frequent+Union Army corps per army 1 8 3.71 3 divisions per corps 2 6 2.91 3 brigades per division 2 5 2.80 3 regiments per brigade 2 12 4.73 4
Starting at the regimental level, commanders had a staff of officers to help with the administration of their unit. Regimental staff officers were chosen from among the unit's lieutenants, while higher formations were to have a representative from the armies' respective War Departments. General officers were also allowed a personal staff of aides-de-camp and a chief of staff. Neither side had an effective way to train staff officers however, and so their competence tended to be based on how much experience they gained. Furthermore, with some exceptions there were no enlisted personnel authorized to assist in carrying out the logistical work necessary to keep these units supplied. Either civilian workers had to be hired or infantry soldiers detailed to handle these functions; the former tended to be unreliable while the latter lessened the combat effectiveness of their units.Gudmens (2005), p. 7United States Army Logistics, 1775-1992: An Anthology. (1997). United States: Center of Military History, U.S. Army. p. 198
Infantry were accompanied by a train of wagons carrying the supplies they would need for a given campaign, although it was often necessary to supplement this by foraging or pillaging. The exact number of wagons needed depended on the number of soldiers and other factors, with commanders seeking to strike the right balance of sufficient supplies without slowing down the army with unnecessary wagons.United States Army Logistics, p. 206-208 Once an ambulance corps was set up, infantry would also be accompanied by a number of ambulances to carry away the wounded (a task otherwise assigned to musicians).
Tactics