The Battle editor, whilst not being as durable as I would like and with a tendency to CTD when I add too much road, is good for adding historical battles - but as Halfthere says that simply isn't an area that RTW modders have concentrated on (though some mods are rediscovering them as a precursor to a full release).

Ingenious as we are, though, it is our way of generating .wfc files which we can use for unique tiles both on the campaign map and in custom battles.