Soldiers spent a lot of time drilling and learning how to manuever on the battlefield. The primary source for infantry drill in the United States Regular Army before and during the war was "Hardee's Rifle and Light Infantry Tactics." It was written by William Joseph Hardee while he was the "commandant of cadets" at West Point (1856-1860).
"Tactics" was a must read by newly minted officers. It updated the "school of the soldier" and "manual of arms" to reflect the introduction of percussion rifled muskets during the 1850s. Reading Hardee's Tactics today provides important insights as to how Civil War units were drilled and led on the battlefield.