How would satellite surveillance and communications change the Second World War?
Short answerThey would transform warning and coordination and sharply shorten the war if held by one side, while exposing major Allied preparations if both sides had them.
NotesThe Allies could observe ship construction, troop concentrations, airfields and operational preparations across Germany, Italy and Japan. Satellite communications would move detailed information rapidly and securely between commands. If only one side possessed that network, the war would become much shorter because Axis movements could rarely achieve surprise. When the counterfactual gives the same system to the Axis, it becomes equally dangerous to Allied operations because the buildup for D-Day and the location of major fleets would be visible.