New suggestion coming your way!
So currently, if a player doesn't want to fight a PvP battle, you pay off the enemy. The problem I have found with this mechanic is it is very annoying / tedious making sure every single army / your town has enough gold to pay off a attack. My suggestion would be to eliminate the need to carry gold for payoff's in your army. And make it so any gold in the empire can be used for a payoff.
Unless of course you intended this side effect in the design, to make it something players have to keep a eye on at all times if they want to pay people off.