Once again, I do not feel that I can do justice to a topic about which I have little expertise. I do, however, feel that the reader needs an understanding of the weapons that fought these battles. So I will turn to the experts to explain them:
Personal weapons:
https://en.wikipedia.org/wiki/Rifles_in_the_American_Civil_War
The breech-loading SHARP’s:
ARTILLERY:
https://www.essentialcivilwarcurriculum.com/civil-war-artillery.html
Basic facts:
http://www.civilwarartillery.com/
https://www.battlefields.org/learn/articles/10-facts-civil-war-artillery
https://www.britannica.com/video/195082/types-artillery-American-Civil-War
Like the modern tank, CW-era artillery was a line of sight weapon. IOW, one had to see what was being aimed at. The human factor, as well as terrain, set the limit of accurate fire at about one mile. Even then, the artilleryist was mainly shooting at an area: “The enemy is behind that wall. I’m aiming at that wall.” Today, artillery is a long-range stand-off weapon. It can, with reasonable accuracy, place a shell on target at distances exceeding 18 mile. Artillerymen rarely see their target. It is a coordinate on a map. Ideally, there is a spotter, a forward observer in radio communication who can assist in adjusting the aim for better accuracy.
In that era, cannons were in the developmental stages that could fire somewhat greater distances. There was a British designed (Whitworths) breech-loading cannon that could fire up to six miles. Also innovative for the day, these were made of steel not cast iron or bronze. The limiting factor was being able to see six miles. One obviously had to be on an elevated position to do so. To a soldier of that era, 18 miles was an unfathomable distance. GEN Meade’s HQ was near Taneytown a mere 12 miles south of Gettysburg and yet he had no idea what was occurring in the battle on 1 July.
Fortunately for the cannoneers, infantry tactics of the day called for massed formations. The shells only had to fall within a 10×10 square of men to do their damage. The challenge was to keep hitting that square as it moved. One reason why cavalry was so feared is that it could out-maneuver those shells.