If you know you are about to declare war on another civ, try doing this:
Just before you declare war, trade all of your opponents gold to you in exchange for a higher amount of gold per turn. They will accept, and then you get the money on a promise. Now, declare war. This will make your promise void, leaving you with no less gold coming in per turn than you had before. Meanwhile, your opponent is going to be penniless, and fighting alone against your awesome army.
No need to thank me.
Just before you declare war, trade all of your opponents gold to you in exchange for a higher amount of gold per turn. They will accept, and then you get the money on a promise. Now, declare war. This will make your promise void, leaving you with no less gold coming in per turn than you had before. Meanwhile, your opponent is going to be penniless, and fighting alone against your awesome army.
No need to thank me.