Mission 21S: Battle Mystery! (Sami) (2)

Turn 1: Infantry Relocation & Naval Engagement
You start with Sami on the eastern island, and Drake has an extra anti-air unit near your infantry. Your main goal is to get those infantry units to the southwest island. On Turn 1, move your infantry three tiles north. Immediately send at least one transport copter over to pick them up. You'll fly them out next turn. Because Drake has so much anti-air on the eastern island, your battle copters there are mostly useful for escorting the transport copter out, not for direct attacks. Take these three copters as far northwest as you can. Simultaneously, with your navy, take down Drake's submarine on Day 1 using your battleship and your own submarine.

Turn 2: Naval Defense & Positioning
On Day 2, you'll want to retreat your naval units westward, getting them out of Drake's battleship range. Dive your submarine to keep it safe. Also, move your rocket unit northeast to get it into a better firing position. This sets up a stronger defensive line.

Securing the Southwest Island
Now, take the transport copter carrying the infantry across the western part of the sea. You should be able to reach the southwest island in one go. Landing here fully secures the win condition for the mission.

Naval Combat Strategy
While your infantry is on the move, your navy needs to handle Drake's forces. You're up against two battleships (one is southeast of your starting island), three submarines, and three cruisers. Use the unit matchups to your advantage: Battleships and rockets are great against battleships and cruisers, while your cruisers are effective against submarines. Your submarine can also help against battleships.

Achieving an S-Rank
To get that coveted S-rank (aiming for 300 points), focus on removing Drake's cruisers. This will make it much easier for your transport copter to escape and generally improve your power score.