No mention of artillery horses? They weren't glamorous but in their anonymity were essential for the movement of the "long arm of the army."
According to the 1864 Field Artillery Tactics manual, each (Union) battery had about 110 horses; six for each gun carriage/limber and each caisson (normally six guns and at least six caissons per Union battery) plus horses to pull the battery wagon and traveling forge. Each horse could pull about 1,600 lbs for 23 miles per day, while an average march was 16 miles in 10 hours. For all this work, the horses were supposed to get 12 lbs of grain (oats, barley, corn), 14 lbs of hay, and 4 gallons of water. There was one driver for every two horses in the battery. The rest of the battery personnel normally marched to ease the load for the horses; when speed was necessary over short distances, the cannoneers could ride on the limbers and caissons but this wasn't done often due to the drain on the horses. Each battery was allowed a couple of farriers to keep the horses shod (using the traveling forge.)
Due to hard work and disease, life expectancy for the battery horses was under 8 months. In battle, the horses were a prime target of the enemy infantry; shoot the horses and the guns couldn't be pulled away quickly, so the battery could be overrun easier and the guns captured (a feat valued as much as capturing an enemy flag). At Chickamauga, my ancestor's battery (3rd Wisconsin) lost 33 horses and 5 guns; at 6 horses per gun, you can see why 5 guns would be left behind. As caissons were normally placed behind the gun line, their horses were less likely to be killed.
After Chickamauga, the seige of Chattanooga ensued. Per the 3rd Wisconsin Battery history:
Immediately our horse feed became scarce and grazing was soon used up; some of the boys would crawl through the lines and pull grass to feed, while they would be in the shelter of anything to screen them from sharpshooters. They would put the grass in corn sacks and drag them in behind themselves to our own lines. The rebels were in a short range but never shot anyone, undoubtedly thinking it was surrender or starvation in a short time. The little corn soon disappeared and the horses in the best condition were sent to Bridgeport [sic] to save their lives; many had already died tied to trees or posts, which they knawed as long as they had strength. During the siege 10,000 horses and mules died of starvation.
My ancestor was detached OCT-NOV 1863 from the now useless battery (one gun left) to take the remaining horses to Stevenson, AL (possibly Fort Harker) where adequate feed was available to keep them alive. Family lore says that PVT Massuere was a quiet and unassuming farmboy who apparently enjoyed the company of his horses more than that of many of his battery mates.
My praise and honor goes to those unsung animals of countless artillery batteries on both sides of the fight.