Cavalry in the American Civil War was a branch of army service in a process of transition. It suffered from emerging technology threats, difficult logistics, and sometimes misguided or inept commanders. Nevertheless, it played important roles in many Civil War campaigns and earned its place alongside the infantry and artillery combat arms.
There were four types of mounted forces prevalent in the Civil War.
At the time of the Civil War, the cavalry had five major missions, in rough priority:
This represented a change from previous eras, in which offensive action was the primary mission. In the Napoleonic Wars, for instance, there were instances of massive cavalry charges used for tactical envelopments of infantry formations. The technology of the rifled musket, which emerged in the 1850s, put an effective end to this practice. While swiftly moving cavalry could overwhelm infantry whose weapons fired accurately only 100 yards, the infantryman with a rifled musket (accurate to 300 yards or more) could fire multiple rounds in the time it took the cavalry to reach his position. A horse and rider were easy targets for these shots.
Offensive actions were certainly not unknown, however, but they were more frequently employed against enemy cavalry than against infantry. Examples of offensive actions include the Battle of Brandy Station and the Battle of Yellow Tavern; cavalry versus cavalry examples include the First Battle of Bull Run and Elon J. Farnsworth's ill-fated charge on the third day of the Battle of Gettysburg.
Reconnaissance was the key to effective cavalry, as it remains today in modern armies (although modern cavalrymen use light armored vehicles or helicopters instead of horses). The cavalry serves as the "eyes" of the army. Reconnaissance was a crucial component in the Gettysburg Campaign, where cavalry under Union General Alfred Pleasonton attempted to find the wide-ranging Army of Northern Virginia on its invasion of the North, and Confederate cavalry under J.E.B. Stuart effectively employed counter-reconnaissance to screen passes in the Blue Ridge Mountains and hide Robert E. Lee's movements.