In the Camp / Army Management screen, there is a button marked "SUPPLY". How much do I need? How does it work?
If I buy 2,500 supply and go into battle I get one supply wagon with an unspecified amount of supply. If I buy 35,000 supply and go into battle I still only get one supply wagon with an unspecified amount of supply.
2,500 supply = one supply wagon
35,000 supply = one supply wagon