Before someone edits my edit: automatic weapons were not used in the ACW for the most part, the primary weapons were muzzleloading rifles, both for musketry and cannons. The Gatling gun was expensive, unreliable, jam-prone, and hardly ever issues in significant numbers. The ACW was also fought by forces which lacked reconnaissance ability (little cavalry, little balloons) and didn't have anywhere near the means of ww1 european powers (this was before the US became a serious industrial power). A few trenches in Virginia also doesn't show anything of the scale seen in world war 1. The only serious close equivalent would be the Boer Wars.