Strategy:
Cripple the US pacific fleet.
Grab all the pacific islands.
Weaken the Americans as they fight their way across the Pacific.
Annihilate the US fleet in a decisive battle.
???
This is known as the Southern Strategy, which was favoured by the navy.
The army favoured the Northern Strategy. However, the Northern Strategy derailed after the Japanese army got trashed during the battles of Khalkhin Gol.
The Japanese army and navy weren't really cooperating, more like competing against each other. (That was one of the reasons why Japan didn't have an independent air force. Both weren't very keen on setting up another competitor.) Once the Northern strategy didn't work, the navy got enough political support to pursue the southern strategy.
The Japanese were well aware what they were up against. They knew America would be a formidable enemy. However, they only had bad options to choose from. So they picked the least bad option.
What were the options?
- Withdraw from Manchuria and China - unacceptable
- Continue the conquest of China - They did that, but the conquest was already stalling
- Pursue the Northern Strategy - had already failed
- Submit to the demands of the US - unacceptable
- Do a surprise attack on the fleet in Pearl Harbor, to try to force the USA to accept the destruction of the fleet and the consequent inability to do anything about it as fait accompli.
The Japanese were well aware they had to strike fast and hard to accomplish that. As surrender was not in their vocabulary, they choose the least bad option, being the attack on Pearl Harbor. Even Yamamoto himself said Japan would have 6-12 months to accomplish their goals. After 12 months the USA would outproduce and outgun Japan in any field. With hindsight: he was right, almost op to the day...
What went wrong? The attack itself, of course. The Japanese embassy wasn't going to hand over a declaration of war, as has been suggested by many. About 30 minutes before hostilities were to begin, they were to break of negotiations. Not to deliver a declaration of war. The official declaration of war followed one hour after the attack. Even if the Japanese diplomats followed the plan exactly, it would still have been considered a sneak attack by the American public.
Analysis: Clearly, the plan was off the rails by the end of Midway (somewhere around moving from 2. to 3.); and it seems near impossible to imagine Leyte Gulf ending with a resounding Japanese victory.
Midway was indeed the turning point in the Pacific War, but even a Japanese victory would merely have postponed the inevitable. Supposing the USA lost that battle and all carriers, they were already building 12 replacement carriers. The Japanese lost 4 carriers, and weren't able to replace any of them. Partly because they lacked the industrial resources, and partly because they simply lacked the pilots and mechanics to replace what was lost.
They were able to launch two new carriers (one by converting a super battleship under construction into a carrier), but they didn't have the planes or the pilots to fly them, the mechanics to service the ship and the planes, not even the enough fuel. Either to sail the ships, or to fly the planes for both. Remember that the Yamato was on a one way mission to Okinawa. At that time Japan didn't have enough fuel for anything else.
