I imagine this is probably known by some people already however...

In playing total conversion mods I was bemused to find not only the same old custom battle maps at the top of the list but to also discover that they look pretty much the same in the mod (even though the map and therefore the coordinates would have changed). The Macedonian Watchtower map, for example, still had that Watchtower on - even though whatever tile might be referenced in custom_locations.txt can't have a Watchtower.

Obviously, in retrospect, the game wasn't sourcing this custom battle from custom_locations.txt it was doing it from the data\world\maps\custom\ folder - which are the 'special' maps with features.

Thanks to Myrddraal's efforts with custom tiles we know how to get a map.wfc file:
https://forums.totalwar.org/vb/showthread.php?t=43149

And it's not difficult to write your own descr_battle file (use the others in the custom folder for guidance) or get it out of the battle editor.

The practical benefit of all this is to allow custom battlemaps with all the potential features that go along with them (towers, cities etc.) _without_ the set starting forces of historical battles and _without_ having to put them somewhere on your campaign map.

It's a small market I know, but would be useful for heavily customised settlement maps which can't be used as dynamic cities for the campaign map.