New technologies played a significant role in how the Civil War was fought, and where it was fought.
The most significant technological innovation impacting where the war was fought was railroads. Railroads had made it possible to transport large numbers of troops and large quantities of equipment in a relatively short amount of time. As a consequence, many battles were fought in relatively close proximity to railroads. The Battles of Bull Run, and Antietam were close to Railroads, and the Union goal in all three (there were two battles of Bull Run) was to capture key southern Railroads.
The breach loading rifle was another innovation that impacted the war. Muzzle loaded muskets took 90 seconds to reload, and were only accurate up to 50 ft. Rifling (invented just prior to the Mexican American war) had nearly doubled the range, but reloading was still time consuming. The invention of breach loading shortened reloading time down to only 30 seconds. This rapid rate of fire, coupled with a range close to 100 ft made battlefields larger and reduced the significance of blade weapons (sabres and bayonets). It also contributed to an increasing use of "sniper" tactics.
Relatively late in the war, another invention further increased the range, accuracy, and deadliness of gunfire. Cone shaped bullets replaced musket balls. These projectiles took far better advantage of rifling improving range and accuracy to over 100 ft. These projectiles also tended to hit faster and penetrate deeper making gunfire deadlier.
Also late in the war, almost too late to have much influence, was the repeating rifle. Until 1863 rifles had to be reloaded after each shot. Combining revolver action with rifle design led to a rifle that could fire six shots without reloading. New innovations in the carbine rifle developed another way of fitting multiple shots in one loading, this shortened the firing interval to 5 seconds, and played a significant role in the Battle of Nashville.