Hard bread (hard tack) is not what I mean, I sent this to the gineral but should have posted it. Now It is a bit older than our period, but I understand the regs didn't change much. This is from "Feeding the Frontier Army. 1775 to 1865 By Barbabra K. Luecke. On page108 it has Article 27 of the 1825 regs. Reg 202 States that "The troops ought not to be allowed to eat soft bread, fresh from the oven, with out first toasting it. This process renders it nearly as wholesome and nutritious as stale bread."
I continue to search my referances, but I know I have seen that bread was to stale a day or so before eating where possible. This might have been in Civil War books from the Library.
It is one of those mysteries that only a food historian would even worry about. I have fed my unit much fresh bread in the past.