There were over 23,000 casualties at the Battle of Shiloh, which will have been fought 150 years ago this Friday.
In the end, it actually seems to have come down to starvation. Lee was "smarter" as a General than Grant, but Grant was able to cut off supplies so that Lee literally couldn't feed his men.
Game over after that.
I suppose the country lying between Corinth and Pittsburg Landing could boast a few inhabitants other than alligators. What manner of people they were it is impossible to say, inasmuch as the fighting dispersed, or possibly exterminated them; perhaps in merely classing them as non-saurian I shall describe them with sufficient particularity and at the same time avert from myself the natural suspicion attaching to a writer who points out to persons who do not know him the peculiarities of persons whom he does not know. One thing, however, I hope I may without offense affirm of these swamp-dwellers - they were pious. To what deity their veneration was given - whether, like the Egyptians, they worshiped the crocodile, or, like other Americans, adored themselves, I do not presume to guess. But whoever, or whatever, may have been the divinity whose ends they shaped, unto Him, or It, they had builded a temple. This humble edifice, centrally situated in the heart of a solitude, and conveniently accessible to the supersylvan crow, had been christened Shiloh Chapel, whence the name of the battle. The fact of a Christian church - assuming it to have been a Christian church - giving name to a wholesale cutting of Christian throats by Christian hands need not be dwelt on here; the frequency of its recurrence in the history of our species has somewhat abated the moral interest that would otherwise attach to it.
-What I Saw of Shiloh, by Ambrose Beirce
Could be the defining example of “the fog of battle”.
http://www.online-literature.com/poe/2037/
Add to that the unintended consequences of general order eleven which depopulated and stripped the western Missouri border counties of all humanity.
And this was just in western missouri and eastern kansas - before the war.
The Civil War Era (1854 - 1865) took more lives than 750,000.
"Order No. 11 and the Civil War on the Border",by Albert Castel
http://www.civilwarstlouis.com/History2/castelorder11.htm
In addition to the human casualties, The South felt the
effects of The War Between The States for 100 years afterward.