Where is the war against the Edo Tensei people being fought?
If we are to follow the images and information we are given. It should be somewhere in between the Lands of iron and an island in the Land of Lightning
This is the current ninja world map.

source of image

Below a piece of the tactic explanation showing a piece of map


Looking at the 3 borders in the tactics. Taking the angle shape, and the information that it is between the lands of iron and the floating turtle.



This would be the most logically location for it to be occurring