subs - first strike than submerge?

[sala33]

my sub is being attacked by a bunch of boats (no destroyers). can I take a first strike than submerge right away without battle. or if i take a first strike i have to participate it combat?

[Krieghund]

You either submerge or fight - not both.  If you take your surprise strike, you have to suffer the return fire (unless of course your attacker is a single ship that's neither a sub nor a battleship and you hit it).