This is a BtS question.
I'm building a late-game naval stack to attack Russia. One of my advantages is possessing Rocketry, when no one else has even got Artillery yet. I'm thinking that it might be a good idea to add an Attack Sub or 2 to the stack, because they are +50% versus Submarines, and I'd rather have them defending my stack versus Submarines at STR 45 + promos, as opposed to a STR 30 Destroyer or a more expensive STR 40 Battleship.
However... I note that Subs and Attack Subs are both flagged as "Invisible to most units" in the Civilipedia. I know that it's pointless to use a Stealth Destroyer as a stack defender because attackers will bypass it (it's invisible, and moreover it doesn't see Subs), and I'm wondering if the Attack Sub is similar. So my question is... under what circumstances will an Attack Sub defend a stack?
- when the stack is being attacked by another Sub, and it is the best defender?
- when another ship attacks and it is the best defender, regardless of whether the attacker can see it?
- both of these?
- neither of these?
- something else?
Any insights would be appreciated.