If the Japanese had managed to achieve victory during the Battle of the Coral Sea, the Japanese would have performed an invasion of Port Moresby in New Guinea, similar to this one. This is also one of the few maps in the game which secondary objectives can fluctuate almost randomly - however, in the end, the above objectives are what will count for the gold medal, and subsequent objectives will give you some naval supplies.
- Capture the radar station.
- Capture the airfield.
- Capture Port Moresby.
- Destroy the specified shore batteries.
- Do not lose any bases to the enemy.
If you haven't played through the American campaign yet, this will likely be the first time you'll play as a troop ship. These ships are large, slow, and lightly armoured, necessitating their protection. They are somewhat difficult to use as they seem to want to launch their LCPs on their own; it is best to simply order them to attack the base you want and let them act on their own accord.
Your Mogami-class will be able to launch a recon plane; it isn't a bad idea to start the mission by doing this. It will give you some additional mobility, and in the event an enemy submarine comes by (as one of the random secondary objectives) you'll be in a good position to sink it. It'll also give you a good opportunity to look around the map and watch the landings yourself.
The first order of business is to take the radar station. This is fairly easy as the station is away from the port and is not heavily defended. Have your cruiser and accompanying destroyers shell the structure with shellfire to help it fall into the neutral category, speeding up the capture process. Once it's in the neutral zone, order your transport ships to attack the building; they will automatically move into range and start launching LCPs. These LCPs are completely AI-controlled, and will charge the beaches to capture the radar station.
You should also obtain a squad of Zeros to protect your fleet with. These are often extraneous and unnecessary, but every little bit helps. Have them hit the designated anti-aircraft emplacements on the island for a quick silver medal. These positions are located in three points - two by the port and one on an isolated island near the airfield. The destruction of these anti-air batteries should be fairly easy.
By now your landing fleet should be in position, and you'll be able to capture the radio station. To help the troops along, have Zeros - or your recon plane - strafe down enemy defences on shore, particularly the bunkers. Artillery fire should also be able to help the capture along as well.
Once the radar station is captured, you'll receive some AI reinforcements in the form of D3A Vals on an attack route to the enemy airfield. These units will, at the very least, occupy the enemy forces and give your own ships enough time to shell the airfield yourself. Neutralize the airfield to stem the tide of enemy aircraft, and then bring forward your landing boats and capture it just like before.
Around this time, you'll receive a few additional secondary objectives. These can vary, but don't seem to count toward your silver medal. On the other hand, they can provide you with naval supplies that can help out a little. Some known objectives involve flying planes to three points around the map, the destruction of a truck convoy, sinking the submarine USS Dolphin, destroying a squadron of Catalinas, and locating the wreck of a crashed Mavis. All these objectives are straightforward and do not require considerable effort.
With the airbase under your control, the enemy will create a small fleet of transport ships. These are escorted by destroyers. More often than not, your allied AI will manage this fleet on its own, but these transport ships can prove problematic in the highly unlikely event that they get through. The hidden objective relies on the elimination of these troop transports before they manage to recapture any of the bases. Destroying these ships should be fairly easy, however.
Proceed into the port and gun down anything you see - shore defences, the shipyards, the airfields, and the command building - to capture Port Moresby. Capturing the port ultimately should be no more difficult that taking the radar tower or the airfield. Once you've neutralized Port Moresby's defences, you should be able to bring in the transport ships for the victory.
Once Port Moresby falls under your control, the mission ends.