It has been said that at Spotsylvania the Confederates used their artillery like giant shotguns. Short ranges and the need to add power to the infantry line necessitated just that. The guns by and large were in the trenches, firing against massed infantry at generally only a few hundred yards.
Perhaps the records can shed some light on this one way or another. Below is a table, taken from the Official Records, showing the amount of artillery ammunition remaining in the ANV ordnance trains on May 18, 1864.
What is interesting about this table is the distribution of rounds, by type, remaining in each Corps trains. Remember this is not the number at the actual batteries. We can assume that the ammo chests for those guns were kept as full as possible. We can also assume that each battalion had a supply of sorts on hand. What that supply consisted of,if it existed at all, we do not know. But once those rounds were fired, whats listed in this table is all that’s available until a new supply arrived from Richmond.
In addition remember that this table is for May 18th. At dawn of that day, the Federals launched an attack with two army Corps against the Second Corps new line behind the Harrison House. This attack was quickly repelled almost entirely by the artillery. We can imagine that the 29 guns employed by General Long that morning used up a significant amount of ammunition. At the same time the Third Corps guns had a substantial artillery duel with their opposite numbers on the Federal side. Whether this table was made before or after the batteries sent back for resupply after those actions we do not know.
Regardless, what we can surmise from looking at this table is not the number, but the type of ammunition that was being used during the battle. For the sake of argument we will assume that each Corps started out with roughly the same number of say, Napoleon shot, when the campaign began. So what would cause a difference between Corps in the number of rounds remaining? The most logical answer would be either the terrain, shorter ranges mean more canister, or the preference of the Commander for one type over another..
The Second Corps numbers could be skewed by the loss of so many guns and their ammunition on May 12, but that would mean fewer guns to consume ammo afterwards. Also its worthwhile to note that those guns were predominantly 3 inch rifles, not Napoleons.
The thing that jumps off the page to us is the shortage of canister. 24 rounds of Napoleon canister, all in 1st and 3rd Corps. 54 rounds of 3 inch rifle canister which was all in 3rd Corps.
And of course Alexander in the 1st Corps was a strong proponent of the howitzer, thus the numbers for howitzer ammunition.
Additionally it should be noted that when the Confederates were expecting an attack on their right on the 19th, Alexander was asked to supply guns as support. The reason being that the artillery of both the Second and Third Corps was “fought out.”
I would think that one of the tasks Confederate Artillery commanders had to contend with at this point of the campaign was fire control. Making sure that the batteries weren’t wasteful of ammunition. How much if at all it effected the battle we will probably never know.