To further pave the way for the invasion of Midway, the Hornet is going to have to be sunk. Fortunately, this mission will be pretty easy, especially if you have previous experience with submarines.
The Type B has received a few changes since Midway. Firstly, it can now launch seaplanes, like most kinds of cruisers. Its two rear torpedo tubes have been moved forward, giving it greater frontal firepower than the Narwhal but absolutely no defences rearward. Avoid rear confrontations with the Type B at all costs.
- Sink the specified transport ships.
- Torpedo the USS Hornet.
- Sink the USS Hornet and all escorts.
- Shoot down the PBY Catalina.
- Destroy all cargo ships.
The enemy convoy you must intercept is dead ahead, but first you must contend with a pair of destroyers. As soon as the mission starts, surface and launch a recon plane to help you see. Have it fly to a safe spot, preferably off to the east, and save it for later.
The head-on attack in Midway works in Pacific as well, although the submarine is rather fickle in making fine adjustments. This makes it difficult in getting the perfect shot off. Destroyers are also more difficult to spot on the surface than before. If you feel you can't make a head-on attack, crash dive to manoeuvring or crush depth to evade them. They aren't your objective anyway - focus on the convoy.
This is also one of the rare times in the campaign at which you are able to lock torpedoes onto another submarine - and potentially destroy it while both of you are underwater. While previously this was only accomplished by moving submarines very close, it is now possible to fire torpedoes at other submarines - at standoff ranges. This can be accomplished by locking onto a submarine as a target, then slinging torpedoes in its direction. The torpedoes will automatically rise and fall to compensate for depth level changes, but they cannot change direction. Underwater torpedo duels are just one of many examples where Battlestations: Pacific sacrifices realism for fun gameplay.
The convoy consists of a few transport ships, troop ships, and most notably, the hospital ship USS Solace. Although the writers of this guide do not condone committing war crimes, you must sink the USS Solace - and all its accompanying ships - to receive the gold medal. Fire spreads of torpedoes to try and damage more than one per pass, and if necessary surface and take pot shots with your artillery. Your submarine can take a few hits, far more than in Midway - but you are still a sitting target on the surface, so crash dive once you get off a few hits.
Once you've sunk all the ships in the convoy (the Americans will brand you "unforgivable" for attacking the Solace, and will make a comment upon its sinking, but otherwise you won't receive any penalty), the USS Hornet and her entourage will appear to the northwest. Nearby you'll also encounter the deadly I-400. This massive submarine - equal only to the ballistic missile submarines of today - is currently pinned down by a patrolling PBY Catalina. This is what you've been saving the recon plane you launched earlier for - have it close in on the PBY and shoot it down with your machine guns. This is far more effective than surfacing and dealing with the PBY as a submarine. In the event your seaplane is shot down, surface and continue to launch them until the PBY goes down.
The Hornet will launch depth charge Helldivers to attack your submarine force as soon as it enters range. Your recon plane, while not a dedicated fighter, can still shoot down several of these before it goes down. The Hornet doesn't seem to replace its losses, so shoot down all aerial depth charges. Aerial depth charges no longer cause the ridiculous amounts of damage they did in Midway, so these SB2Cs can be problematic at most. In the event you lose a submarine, you will take command of one of the other three. Losing all three submarines will result in the failure of the mission.
Once the PBY Catalina is shot down, the I-400 is free to move. It will reload you with torpedoes if necessary, but you shouldn't need them for now. Your next objective is to announce over the radio the American carrier's position to Yamato. This is easily done by simply surfacing. Naturally, you're going to want to do this somewhat far away from the rest of the fleet. It takes about 15 seconds to send the message, so surface far away and be ready to crash dive if necessary. Alternatively, you could try to simply die, take control of another submarine, and use that one to send the message.
Sending the message prompts the appearance of another objective - disable the USS Hornet with torpedoes. A single torpedo hit will slow the Hornet down, paving the way for the Yamato to strike at her without it trying to run away. Torpedoing the Hornet should be relatively easy - with so many torpedo tubes and so many torpedoes (and even more from the I-400), all you have to do is lead the Hornet and fire a wide spread of torpedoes. Only one needs to hit, so fire some at the bow and one at the stern to guarantee a hit. Ships have a much longer deceleration time than in Midway, and torpedoes travel much faster, so a long-range strike from about half a kilometre away shouldn't be too hard.
With the Hornet disabled, the Yamato moves in for the finishing touch. Escorted by a pair of Akizuki-class destroyers, the Yamato can, as your submarine commander says, win this battle single-handedly. You remain in control of the submarines, however, so you may as well put them to use. Have your submarine torpedo the Hornet as many times as possible and leave the destroyers to Yamato.
Yamato makes the mission a thousand times easier - none of the American warships are in a position to stop you, so simply sail in and blow everything to pieces. Utilize those massive cannons to sink the American Fletcher-class escorts in a salvo or two each, and the Hornet is quick to fall to torpedoes or cannonade.
Sink the Hornet and all American ships to end the mission.