Of course I’m not contesting the fact that in the three years you mention, the US bore the lion’s share of the fighting, but to imply that we went it “mostly alone” in the Pacific is not entirely true, and I think Aussie486 will probably back me up on this.
There were two commands in the Pacific Theater, the Pacific Ocean Areas command and the South West Pacific Area command. I assume that when you say “War in the Pacific” you are referring to the Pacific Ocean Areas command, which was as you say a predominantly American undertaking, however there was active participation by New Zealand, the United Kingdom, Australia, Canada, Mexico (!), and Fiji. The British assisted in the Battle of Okinawa, and the fleet was poised to invade right along with us. And indeed, the Occupation was by not only American troops, but troops from the British commonwealth.
http://www.diggerhistory.info/pages-conflicts-periods/other/bcof-japan.htm
The British, Dutch, New Zealanders and Australians took a more active role in the South West Pacific Area, because it was, after all, mostly their land that was being threatened: as you probably know, on the same day as they bombed Pearl Harbor, the Japanese invaded British Hong Kong, Dutch Indonesia, the American Philippines, and Thailand (to use as a base to launch their invasion of British Singapore and Malaya. The recapture of Burma was almost entirely a British undertaking (with some help from the Gurkhas and the Chinese), and would have pushed into Malaya, had not the Japanese surrendered first. The Australians were instrumental in the liberation of Borneo, Timor (assisted by the Dutch), and the Philippines. In the Battle of New Guinea, the Australian army was largely responsible for handing Japan their first land defeat since 1939. Meanwhile, just offshore in the Bismarck Sea, the Royal Australian Air Force assisted the US Army Air Force in devastating a convoy of Japanese troop ships, also sinking three destroyers.
http://www.history.army.mil/brochures/new-guinea/ng.htm
http://www.awm.gov.au/atwar/remembering1942/bismark
The British Pacific Fleet formed about 25 percent of the total Allied strength in the Pacific, with 17 aircraft carriers carrying 300 planes, four battleships, 10 cruisers, 40 destroyers, 18 sloops, 13 frigates, 31 submarines, 19 corvettes, 35 minesweepers, and a plethora of oilers, store ships, sub depot ships and other support vessels.
[i]The British Pacific Fleet was a reluctant ally in the Japanese war. The Americans regarded the defeat of the Japanese as “their” war, and had evolved fleets with “long legs”. This meant that the fleet could remain at sea for extended periods as their supply ships could provide food, fuel, ammunition and other supplies as they steamed. They used atolls as fleet anchorage to carry out repairs. In contrast, few British ships rarely remained at sea for more than eight days, and had become dependent on ports for repairs. The Americans demanded that the BPF be able to be at sea for 20 days per month as a minimum. The BPF had tried to develop their supply and repair fleet to American standards, but often had to ask the Americans for fuel or food when the British fleet train process was unable to deliver.
The command of the BPF was split between Sir Bruce Fraser (fleet operations) and Sir Philip Vian (air operations). The BPF had six new fleet carriers, HMS Indomitable, HMS Victorious, HMS Illustrious, HMS Implacable, HMS Indefatigable and HMS Formidable, but not all were active at the same time because of refits and engine problems. There were two battleships, HMS King George V and HMS Howe. These were escorted by six cruisers and 12 destroyers. The air crews were a mixture of Canadians, South Africans, New Zealanders and British pilots. They flew mostly American aircraft such as the Corsair, Avenger and Hellcat, with a few Sea Fires.
The BPF was initially designated as Task Force 57, under Admiral Raymond Spruance. They joined the Okinawa campaign on March 26, but in early April they were allocated to their own theatre of war in the Sakishima Gunto group of islands north-east of Formosa. The BPF performed well in these operations, even though targets were scarce. The objective was to prevent the Japanese from using the islands to supply aircraft to Okinawa where the kamikaze squadrons were wreaking major damage to the U.S. Fleet.
The BPF pilots (including Lt. Hammy Gray) carried out successful strikes against several airfields. The BFP came under attack from the kamikazes. Both HMS Indefatigable and HMS Formidable were hit, but their armoured flight decks prevented much damage, and the ships were back into operation within a few hours. In contrast, many of the faster and lighter American carriers suffered crippling damage because their flight decks were not armoured.[/i]
Oh, and why “surprisingly strong” insurgency from Vietnam?
Considering that Vietnamese insurgents were somehow able to force the surrender and retreat of the invading and occupying armies of the Song Chinese, the Mongols, the Ming Chinese, the French, and even the Americans, I’d be surprised if the insurgency against the Japanese invaders was anything but strong.