In my current game as the allies against the AI, I started out by sending all my heavy units south out of harms way on December 7th. My premise was the same as yours, code breakers knew of the attack. Instead of sending my untried battle fleets headlong into the fight, I ran away to fight another day. I learned many hard lessons through the war, and the way things changed from history is amazing. The Japanese took all the islands from the Solomons to Noumea. The pivotal battle of the entire war (until now, October 1944) was fought around Suva of all places. I had been counter punching invasion forces with CL/DD SAGs and doing quite well. All of a sudden a large CV force appears north of Suva and sinks an entire cruiser force returning from a strike. Fortunately the US CV's were already on their way to Suva, and after the Japanese bled their CV air groups dry in two days of heavy fighting over Suva, my CV's pounced on them sinking three CV's and a CVL.
As the war went on and I finally took back enough real estate to attack the Solomons, the slaughter of the Japanese cruiser fleet began. As it stands right now ten Jap CV's have been sunk, and well over 25 CA/CL. 1400 or so ships in all ;) I have managed to do something that our admirals never managed to do, and that's lose an Essex class CV. In fact, I have lost 3, all of them to LBA. Rangoon is mine though, and B29 raids are hitting the HI from Saipan. This game has been AMAZING to watch over the last two years of play. Really nothing quite like it out there.
Yes, it is. I highly recommend that you take on a human opponent. That will take it to another level for you, and you will be amazed at all of the misconceptions you can pick up from playing the AI.
I am the Holy Roman Emperor and am above grammar.
Sigismund of Luxemburg