Battlestations: Pacific/Battle of Java Sea

This version of Java Sea is far easier than in Midway. Rather than fight multiple enemies at once in stages, this fight has you fight a bunch of destroyers, then a bunch of cruisers. Not only that, but you also

Primary Objectives Secondary Objectives Hidden Objectives
 * Sink all enemy destroyers.
 * Assist the Japanese fleet and sink all enemy warships.
 * Sink the unidentified Cleveland-class light cruiser.
 * All transports remained unharmed.

Finish this mission to unlock the Tone-class Cruiser.

Your ship starts out in the northern section of the map, with multiple enemy warships to the south. The transports you must protect are off your stern. The observant, however, will notice the HMS Electra closing in from the western side of the map. Use the tactical map to locate her and close in to engage her. Electra is a Clemson-class destroyer, unlike the Fletchers you fought in Midway; not only this, but your ship has been upgraded to a Mogami-class cruiser instead of a Tone-class. The additional firepower is more than apparent here.

A few seconds into the map, your engine will splutter and fail. Quickly open the repair screen and get the engine fixed. Work quickly, but it ultimately proves to be more of an annoyance than an actual problem. Once your engines are done, race to intercept Electra before it causes any damage to your transports. This will earn you your gold medal. Note that there isn't any indication that you've failed or achieved the gold medal, since the ABDA destroyers that are your designated targets will engage the transports if you let them.

Fortunately for you, the ABDA destroyers you'll encounter are all of the Clemson-class, so you'll have very few problems disintegrating them. Lock onto them and send them to the bottom with your powerful cannons. You can use your torpedoes against these guys, or you could save them for the last wave.

Versus DeRuyter
The final enemy wave consists of cruisers - most of them of identical to the De Ruyter. Sail forward and engage them - they're not that big of a threat, being a tier lower than you (CLs versus your CA). Charge forward and annihilate everything. Around this time, the group of bombers from the previous mission will target the strongest unit the enemy has - the HMS Exeter. The bombers will likely cause quite a bit of damage to Exeter, or miss it entirely with their bombs. Every little bit helps, but bombers or not, you should still be able to manage Exeter without too many problems.

Once Exeter is done, sink the remaining targets (including De Ruyter) to finish the mission.