Tactics lagged behind technology. All with a few years tremendous leaps in technology were made, sending centuries old tactics into tatters. Rifling of gun barrels - Tactics were based upon a 50-100 yard accuracy of rifles. It suddenly became 1,000 yards. Trains - Troops and supplies could be moved about in mass and no longer limited to how fast an army could march. Telegraph- Communications that used to be a rider on a horse could now be made instantly over hundreds of miles. Industrial Revolution- now things could be made in mass - guns, ammo, farm equipment to supply food, etc etc. Other things to minor effect - use of balloons for air recon, gattaling guns, dynamite, TNT. Near the end of the war tactics were finally catching up. They became very much like what we saw 50 years later in WW1, trench warfare. Battlefield medicine caught up quickly. If you lived long enough to get to a field hospital you had the same survivability rate as a Vietnam combat soldier did. What’s ironic is the Europeans laughed at America’s casualties of the Civil War saying how inept we were. But just as our technologies outpaced our military tactics, the same thing occurred with the Europeans in WW1. And then the carnage was even greater.