What do you hit each with?
Because, the best I see is Japan down to 1 carrier and a pair of fighters after all that. (After America counter strikes Hawaii and sinks the BB there, btw.)
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SZ 30:
British Defending: Fighter, Carrier, 2 Transports, Submarine, Destroyer
Japanese Attacking: 4 Fighters, Carrier, Battleship
(Fighter from SZ 50, Fighter from FIC, 2 Fighters, Carrier, Battleship from SZ 37)
Attacker: Fighter, Battleship Remaining. (Note, you’d have to sink the Carrier to be assured of sinking the rest of the British Fleet.) 73% Odds to win with at least a battleship remaining.
SZ 52:
Americans Defending: Fighter, Carrier, Submarine
Japanese Attacking: Battleship, Destroyer, Submarine, Bomber
(Aircraft Carrier from SZ 50 must be available to go to SZ 38 to retrieve fighters, thus no legal landing zone for the fighter housed in Japan to hit SZ 52. Carrier also cannot attack SZ 52 since it must be available to retrieve fighters in SZ 38.
Japan survives but with either a bomber and a battleship or a destroyer and a battleship (possible bomber survival as well.)
This can easily be counter attacked by Battleship, Transport, 2 Fighters and a Bomber sinking another Japanese warship.
To be honest, Switch, I’m not seeing a viable attack on both SZ 30 and SZ 52 by Japan. Not once you factor in luck. SZ 52 can easily scorew 3 hits on round 1 defense or you can easily score only 1 hit in round 1 yourself allowing for a round 2 or even 3 defense in SZ 52. Fighter dies last, of course.
Meanwhile, you have to tie up two aircraft carriers and a battleship for SZ 30 and, while you might come out miles ahead in the battle, you might also get your buttocks handed to you. You’re attacking a lot of high defense targets and there’s fodder in there as well. Not to mention one of the ships is a submarine that can only hit your warships, might come into play forcing you to lose a warship instead of a fighter, it probably wont.
Anyway you slice it, if Japan hits both fleets, they’ve effectively given themselves a vasectomy. It can be reversed, but not without a MAJOR cost and a bit of luck, IMHO.