Civil War no doubt, most other battles/wars someone had a superiority - except in the middle ages, but in the middle ages you weren't getting your bellybutton shot at while you were swinging your mace around.
In the Civil War, everyone lined up, fired at the enemy who was also lined up, then someone advanced. Many dropped on both sides, reload as fast as possible, then get another shot off. After that, bayonett time with people still being shot at. This was close quarters combat.
In an open field, one sided advanced with canon balls and a wall of shot coming at them.
Maybe there was something in europe equivelant to this? French Revolution?
Study your history. Perhaps many Americans are not aware of it, but I suggest you look at the Napoleonic wars and in particular the battles in Flanders, Portugal and Spain between the British (+ allies) and the French (+ allies). The warfare you decribed above was not an American invention - it was a European method honed to deadly efficiency by centuries of practice.
Have you forgotten Waterloo? Even just taking into account the 10 hour battle itself and excluding Quatre Bras and the other preliminaries, there were 64,000 casualties on both sides.
At Borodino there were 74,000 casualties.
The muskets reloaded faster than the older ones, and furthermore muskets were phased out in favor of rifles, which were far more accurate.
Rifles were in use in the British army in 1806 I believe, when green coated skirmish regiments like the 60th and 95th would harry the enemy at long distance, as they attacked.
While the ACW saw widespread use of rifles, whose accuracy was greater than the smooth-bore musket carried by line infantry 60 years earlier, the rate of fire was not. Breech loading weapons were a relative rarity and were out-numbered by the traditional muzzle loading type. An average British red coat battalion of the Napoleonic era could fire 4 shots a minute - and at the ranges they engaged accuracy was irrelevant. A few devastating volleys of battalion fire would kill an attack dead - as the French columns learned time and time again. In attack, a volley would be fired before closing with the bayonet.
I believe grapeshot was used for the first time in the Civil War, I could be wrong on that though
Wrong, I'm afraid. Grapeshot had been around for a hundred years or more before the ACW - primarily used on ships although not always so. Other methods had been developed for land. The British army used case shot (hollow cannon balls filled with musketballs around a charge), cannister (thin walled cannisters filled with musket balls which would split apart at the cannon muzzle), howitzers etc. Artillery was very advanced.
The ACW did not see large cavalry actions to the extent that the Napoleonic wars did. Cavalry was losing its influence as a major battlefield force, but back in Wellington's and Napoleon's day, the cavalry were a superlative killing machine and could decimate broken or exposed troops in short order.
Overall, the ACW did see the introduction of more lethal weapons but I wouldn't say it was the final word in pre-20th century warfare.
I'd say a later battle was pretty intense too - Rourke's Drift. To be in those British soldier's shoes must have been terrible. Didn't they award a bucket load of Victoria Crosses afterwards?
