[Marco]

I completely second the system explained by PvK, but I think there is some more point to solve:
1. What happen if the retreat movement is in a strategic location with others enemy units, may be from another player ? In this case another tactical battle begins among three or more players, very difficult to handle with the new retreat option. A possible solution: prevent retreat in strategic locations with enemy units.
2. The direction of the retreat in the strategic map: a “forward retreat” tactic to bypass enemy units, let say a enemy blocking fleet at a warp point, must be allowed or not ?

Marco