The default setting for fog of war in XGM is "on" (actually, TRUE). One of the interesting things about playing XGM way over in the East, like I am, is that I have no idea where things are. It's like I'm a newbie again!
I'm not sure if you can turn f.o.w. back on after it's been off without restarting the campaign, but making sure to turn it back on beforehand. The FOG_OF_WAR switch is pretty near the top of the Preferences.txt file in your XGM folder. Maybe if you make it "TRUE" (without the quotes) while the game isn't running, it will be in effect next time you start the campaign.
[This message has been edited by mikecz (edited 11-05-2008 @ 08:17 PM).]