We have this discussion at least once a year.
Of course, you're a Yankee, because most scenarios have this problem for rebels.
I and others have offered solutions, but we still have the "great cosmic artillery ammo depots" in the sky.
You may find these archived threads informative as some go 4 pages of discussions.
I also recommend that you put "artillery supply" into the "Search" function on this site and check the box for archives. More than you will ever read...[;)]
http://www.wargame.ch/board/acw/topic.a ... C_ID=13204
Supply Problems While Seeking Realism
http://www.wargame.ch/board/acw/topic.a ... C_ID=11952
Artillery Crews
http://www.wargame.ch/board/acw/topic.a ... C_ID=10580
Ammo, ammo, ammo! Much More Ammo!
http://www.wargame.ch/board/acw/topic.a ... C_ID=12062
Future engine enhancements
BG Ross McDaniel
2nd Bde, 3rd Div, III Corps, AoG, CSA
Make yourself sheep and the wolves will eat you." -- Benjamin Franklin
"A society of sheep must in time beget a government of wolves." -- Bertrand de Jouvenal
“It is useless for the sheep to pass resolutions in favor of vegetarianism while the wolf remains of a different opinionâ€