Okay, but this is not Pacific, it’s Anniversary.
Just like in Pacific, Submarines cannot hit planes, they cannot be attacked without destroyers and they can slip under enemy units if no destroyers are present, BUT!
Submarines cannot stop surface ship movement. I can glide past any submarines on the board I want too.
They cannot stop me from loading a transport or unloading a transport (in other words, they do not make a sea zone hostile by themselves.)
They defend at a 1 and can be attacked by a destroyer and 40 fighters if you want to attack them as such.
Basically, they are completely and utterly useless units to build. They cannot hit battleships and carriers since you can elect not to receive submarine hits on those units (according to the rulebook in the box, it might be different in the FAQs now.)
To put them in a nutshell:
Submarines can shoot Submarines, Transports, Destroyers and Cruisers.
Submarines do not make a sea zone hostile, they can be completely ignored.
Submarines cannot pass through destroyer patrolled sea zones (all others they can)
But hey, they cost less than transports and barely more than tanks now! (BTW, I do bring them, having one or two in your fleet can be useful just for the fact they force the enemy to put a destroyer in the water.)
The ruling, last I heard, was that to get the National Objective the allies had to control any orange territory. That would limit you to:
Carolines
Formosa
French Indo-China
Iwo Jima
Okinawa
Japan
Territories that start as conquered territories do not count since you are not taking a Japanese territory, you are liberating someone’s territory.