Why was the Civil War so bloody? Why were the casualty numbers so great and horrific?
The answer is simply due to the fact that technology outpaced the tactics used in battle. The tactics used during the Civil War were tactics that were designed for infrantry that did not have accurate weaponry at their disposal- smoothbore muskets. Essentially, based on outdated Napoleonic tactics that had long been taught at West Point and other military training centers. These tactics required massing infrantry shoulder-to-shoulder, marching within a very short distance of the enemy and firing in unison. This premise, therefore, allowed infrantry to compensate for their weapon inaccuracy by concentrating fire in one general direction or area.
The problem was of course that by the time of the Civil War in 1861 many musket barrels were grooved and no longer were smoothbore. Now, the round left the rifle like a football leaves the arm of a quarterback- in a tight spirral. Soldiers could now fire at greater distances, with devastating consequences. By the end of the war many Union soldiers were issued “repeaters”, which allowed them to fire multiple times before reloading.
The result. . .by not changing tactics the casualties for both sides during the war, especially on advancing armies facing well-entrenched defensive positions were truly horrendous.