All units can have three states of visibility for the opponent:
- Visible (Unit marker)
- Unknown (Diamonds marker)
- Invisible (Not shown)
Army Command: Adjacent Land/Air units are shown with an Unknown marker until either you or they commit an offensive action or their unit is revealed by the use of Intelligence. If a manoeuvre has taken place by you or the enemy, the unit will become visible for 2 turns, after which it will return to become an unknown marker (Large Diamond) as long as adjacency is maintained. If multiple land/air units are in the same region when visible the Large Diamond marker will be replaced by small unit symbols for any engaged units and Small Diamond markers will be added for each unknown unit (showing how many enemy units are in the region) but after 2 turns the markers will revert to the Large Diamond.
If a visible unit moves out of adjacency the unit will immediately turn into an Unknown for two turns after which it will become invisible. Land units do not discover Sea Units.
Bomber Command: When making an Air Mission (regular Bomber Command attack) in a region where an enemy bomber or land unit is based they will become visible for 2 turns. If the enemy air unit is a Fighter or there is an enemy carrier present in the region, the opponents unit will become visible for 1 turns only. If an enemy Fighter or Carrier is present it will prevent any other unit to become visible. If BOTH an enemy Fighter and Carrier are in the same region the Fighter (as long as it's not engaged) will take on the bomber first and keep the Carrier invisible unless a new bomber is sent in after the first attack in which case the Carrier will be discovered as well and will intercept the new bomber wave. You bombers base region is not revealed by you doing bombing missions in other regions.
Fighter Command: When your fighter is making an Air Mission (regular fighter command attack) against a region with only enemy land and/or submarine units, they will remain invisible or in the case of adjacency to friendly land units, the Large Diamond marker will continue to be shown to not give away unit count.
All sea units that enter a region controlled or dominated by the opponent will be shown as Unknown as long as they continue to reside in that region. If multiple units enter the Large Diamond will be replaced by the Small Diamond marker and thus showing enemy unit count without revealing the unit type but after 2 turns the markers will revert to the Large Diamond. The instance they leave for a neutral or friendly region, standard rules apply.
Submarines Fleet: By default invisible and are only visible to your opponents when you do an offensive action, when making a nuclear launch or when your submarine fleet is attacked by the opponent. When becoming visible the visibility only lasts for 2 turns.
Surface Vessel Fleet: By default invisible and are only visible to your opponents when you do an offensive action, when making a nuclear launch or when your Surface Vessel Fleet is attacked by the opponent.
Carrier Fleet: By default invisible and are only visible to your opponents when you do an offensive action, when making a nuclear launch or when your Carrier fleet is attacked by the opponent.