This command will toggle (enable or disable) FOW (fog of war) either in general, or in the province of the specified ID. To clarify, if this command is executed without any arguments ('fow'), it will turn off fog of war completely. If a province ID is specified as an argument, fow will only be toggled for that province.
fow [province id]
|Province ID||Optional. If specified, this will toggle fow in this province only. If not specified, the entire map will be toggled.|