Supply Wagons

Every army has a hidden supply wagon. The supply wagon is contains many vital resources and supplies needed to wage war. The value of your supply wagon corresponds to how much money you earned in the previous turn, so a large, successful army will have a much more valuable supply wagon.

The location of your supply wagon is secret known only to you. Similarly, your rivals' supply wagons are hidden from you.

To steal a supply wagon, the supply wagon must first be uncovered, and then it must be successfully raided.

Discovering Rivals' supply wagons
The best way to uncover a rival's supply wagon is to place a spy in the location you think it is hidden.

It is also possible to uncover a supply wagon if you have a vassal in the location, although this is a small % chance each turn (and it is unlikely that an enemy will leave their supply wagon in your territory).

Once you discover it, you still need to win a raid in that region.

Having your supply wagon discovered
Every turn that goes by, your supply wagon becomes less secure and the chance of it being discovered by rivals or bandits increases. After about 8 turns, the location of your supply wagon is common knowledge and bandit raids are very likely. To 'reset' the security of your supply wagon, move it to a new region.

But, there is also a risk associated with moving your supply wagon. On the turn that you move it, it is vulnerable and the chance of bandit raid goes up for that turn only.

Therefore, there is a balance between moving your supply wagon too often and leaving it in place too long.