- The airfield must survive
- The USS John D. Ford must survive
- The island must not be captured
- Shoot down the G3M Nells
- Launch a preemptive strike on the enemy landing fleet
- Half your air force must survive
- Sink the Tatsuno Maru
- All bunkers must survive
This is primarily a defence mission, but like they say - the best defence is a good offence, so start by launching all four squadrons of P-40 Warhawks and send them to the southwest - where the enemy bombers start coming in. You can try equipping your latter three squads with bombs (the first squadron is already set to takeoff as soon as the mission starts) for later use, but doing so will decrease their manoeuvrability and thus their survival rate against Zeroes.
If you want to have a little fun, sink the oil tanker by the shipyards. The game won't penalize you for friendly fire, and some players shoot non-playable ships in multiplayer, but obviously friendly fire against a controllable unit isn't a good thing.
Defend the Airbase
Escorted primarily by a squad of Zeroes, the G3M Nells are easy targets, and don't shoot back (mostly), so simply get behind them and lodge several bullets in their hulls to send them down. If you've outflown the enemy at Vengeance at Luzon, you should have few problems defending the airfield from these guys. Take command of your planes and split up to shoot down the targets: match the Zeroes on 1:1 odds, and have everyone else deal with the bombers. The bombers are the more important targets, but the Zeroes are the ones the AI will have trouble shooting down, so take control of the Warhawks fighting the Zeroes and fight them. The rest of your squad should be dealing with the straight-flying level bombers and make short work of them.
Ultimately four waves of enemy aircraft come in - the two consist of Nell medium bombers, and the final ones consist of Vals. The last wave is escorted by five, not the usual three, Zeroes. During this battle you'll be forced to fight 3:5 odds against, so you'll probably have issues. Just relax and deal with the bombers first, then mop up the fighters. Failing the hidden objective of losing half your air force is better than losing your airfield and having to start all over again.
The Invasion of Bali
Once all the enemy planes are done, the invasion fleet appears. It's a really big fleet, the biggest one so far - the Kuma-class light cruiser Nagara, three destroyers, and five objective targets: two SB boats, two troop transports, and the Tatsuno Maru oil tanker.
Start with the easy stuff - the oil tanker. Land all your Warhawks and replace them with Devastator torpedo bombers. Send them against the enemy cruiser, and lead the attack personally to ensure the lead cruiser's demise. If you can, sink a bit of the enemy troop transports - the troop transports and especially the Tatsuno Maru are easy pickings for machine gun fire. It doesn't take long to send those ships to the bottom.
Dauntlesses are also capable of attacking the destroyers in particular, but torpedo bombers work just as well. You are equipped with B-25 Mitchells for this mission, but ultimately you won't need them. Most of the enemy warships are too small to hit accurately with level bombers, although since they're there you can have a little fun with them.
The SB boats are pretty easy as well. All it takes is a single torpedo to send them to the bottom, but since your squadron attacks all at once you'll likely overkill it or miss completely. A better choice is, once the destroyers and especially the light cruiser is dealt with, is to deploy PT boats from your shipyard to finish off the enemy ships. Arm torpedoes and, just like the second mission, deploy them against the enemy landing fleet. You should sink all the enemy ships in short order, thus bringing the mission to a close.
If you thought the last two missions in particular were easy, just wait. The next mission is where the game seriously ups the ante. By now you should have finished all the Naval Academy missions, as well as Silent Hunting for the next mission (except if you're on the PC version - Silent Hunting is broken there. An alternative is to play the Submarine Challenge missions).