Civil War During the American Civil War, which lasted from 1861-1865, over 620,000 accounted soldiers were killed. Known as the "the first modern war", historians generally agree that the reason for this was because this was a time of transition for the military. Armies and Navies were still using tactics where they would gather large forces of firepower to bear on the enemy. At the same time, weapons were being developed which were accurate and lethal well beyond any arms of the earlier conflicts. As a result of these two conditions many more casualties were sustained. Add to that the lack of medi