It was a war in which brother fought brother. Where battlefields became slaughterhouses. Where the astonishing technology and ingenuity of a country in the midst of an industrial revolution, was put to the task of making the most destructive killing machines the world had ever seen. More Americans were killed in the Civil War than in all other American wars combined. Ominously foreshadowing the horrors of the first World War, the guns of Civil War became the first truly modern weapons.