No American Caesar
Much has been written on the life of General Douglas MacArthur, from his early career as a semi-official strike-breaker, to his command of the Filipino forces, to his work as Governor of Japan and final disgrace during the Korean War. It is a highly controversial subject, but it is unquestionable that he had a huge effect on the Pacific War. In my belief, he was responsible for the war lasting a few months or even a year longer.
Certain facts are beyond easy dispute;
So, how might the war proceed without him? Let’s have MacArthur shot by a Japanese sniper during the Philippines Campaign. MacArthur might have encountered one of them during a visit to the front lines, assuming he made one at the right time. So, a Japanese sniper puts a bullet though MacArthur’s head.
Barring a minor miracle, the Philippines will still fall. They may fall slower or faster without MacArthur; that’s something its impossible to determine. The American troops will still go into POW camps, while Australia will need someone to assist in the defence.
(A radical offshoot of this timeline would have an invasion of a weaker Australia, as MacArthur was very aggressive in getting weapons for the nascent defence forces. The Japanese would still face MAJOR logistical problems, so I’m going to leave that out of this timeline.)
The major effects come after Midway, assuming that Midway still happens in this timeline. Without MacArthur, the Americans can have a united Pacific Command, and launch a more determined campaign from Midway-region up to take the islands towards Japan itself. Guadalcanal might still happen; Australia will be safe behind American power. The success or failure of Slim's war in Burma will be as irrelevant in ATL as it was in OTL to the final outcome.
In 1943, the Americans launch the major offensive. The Japanese will face a single powerful American thrust, aimed at ending the war as quickly as possible. Instead of the bloody battles in the Philippines, the Americans will attack Okinawa (Midway-Wake-Marianas-Iwo-Okinawa) and end up at Japan itself in late 1943.
Now, in ATL, the atomic bomb will not be ready, even though the firebombing of Japan can start earlier than expected. This has major implications elsewhere; the Americans can open up direct lines to the Chinese Nationalists – who won’t lose their best troops in the OTL1945 offensive – and speed the defeat of Japan through occupying Korea.
The Russians will not be ready to take a slice of the Manchurian cake. The ChiComms or the Nationalists will probably overrun the Japanese garrisons as they’re starved out, but without the 1945 offensive, the Nationalists will probably be capable of suppressing the Communists. Stalin would not be in a position to help – although he might push FDR to avoid aiding the Nationalists – and Mao might end up fleeing to Russia to escape capture.
(Or possibly the Chinese Civil War will begin earlier than expected.)
This leaves America with something of a problem. Japan has not surrendered, even though the cities are being bombed and the citizens are starving. To meet the need for troops for Europe, the Americans will almost certainly starve the Japanese out, bombing away to destroy their cities, perhaps including gas attacks. My presumption is that the Japanese will surrender in early 1944.
This has major effects on the European theatre. Without the requirements of Japan, the Americans can place more power into Europe, which can be used to challenge Stalin if necessary. Berlin may still become Soviet – racing for Berlin would have been harder than Bradley and Patton made it sound – but the overall borders will be drawn more to the West’s favour. The defeat of Japan might tip some Germans into overthrowing the Nazis and suing for peace, or maybe not.
The post-war development of Japan might be more interesting. Without a threat from Korea – united under Rhee – the Japanese won’t have to become rearmed. Someone less…capable than MacArthur might cause more offence in Japan, leaving the Japanese bitter and resentful.