Submarine Surprise Attacks

[Vermin]

1925-1935. How do they work and what should I expect to see?

[thedoctorking]

You are cruising along and suddenly you get a message that such and such a ship was hit by a torpedo. Quite distressing!
This is what screens are for.

[WLRoo]

I think Vermin is referring to the Surprise Attack national trait (Japan only in the un-modded game AFAIK).

It's an unusual one as the others are Surface Fleet (usually with heavy DD support to represent the Japanese attack on the Russian Fleet at Port Arthur) or later a carrier strike (to represent the attack on Pearl Harbour).

But submarines...I can only assume that you kick off with a series of successful attacks on enemy warships.

[f11supertiger]

I've never played the Japanese, and when I do fight the Japanese I like to keep my fleets well away from Japanese bases during fleet precisely because I know surprise attack exists, so I wouldn't know.