After an uneventful April on all fronts, Operation Coronot is given a go-ahead with an aim of landing troops on the Japanese home islands by the end of May. The operation begins with a scramble to pull 1st Special Operations Army from the front at the Red River Delta back to the port of Quang Ngai on the east coast of Indochina. 3rd Army is left dug into defensive positions along the river banks. General William Slim is promoted to commander of the invasion forces, which are comprised of 1st and 2nd Royal Marine Corps, 2nd Airborne Corps, four battleships, two battlecruisers, four aircraft carriers, 24 transport flotillas , and numerous other escorting ships and aircraft.
Land-based bombers provide some protection from marauding Japanese fleets, but only out as far as the Gulf of Tonkin up to Hainan. The fleet will need to travel the rest of the way on its own.
By 22 May, the army is fully assembled at the port. The transports are loaded, and the fleet moves out in unison on course for Japan.
The trip is ultimately uneventful, and no enemy ships are spotted whatsoever. Clearing ‘carrier alley’ around Hainan, the fleet is mostly in the clear. By midnight on 23 May, the fleet rounds Formosa and moves into American-controlled waters.
The fleet arrives on station off the southern coast on 24 May. All carriers launch aircraft and begin scouring the coast for suitable landing sites. The port city of Nagoya looks ideal: not as well-defended as Tokyo, but still offering quick access to both a harbour and an airfield. Unfortunately, while the Nagoya is within range for the transports, the main fleet cannot close to support the landings while keeping enough fuel to return home. The landing area as a whole looks pretty clear, so the go-ahead is given. In lieu of support from the big guns of the fleet, absolutely all aircraft are launched, hitting airfields and ports across the island, as well as overflying and covering the landing areas directly.
On the early morning of 26 May, the invasion begins. Marines very quickly seize nearby territories, while the attack on the port lasts well into the evening. The airborne divisions hold in their transports to act as an afloat reserve, ready to reinforce or counter-attack wherever necessary. They are not needed, though, and the Japanese finally yield after losing over a thousand men after one brutal day of fighting.
With the port secured, the remaining transports offload the airborne divisions and HQ brigades. The main fleet enters the port and quickly refuels before moving back out off the coast to provide gunfire support to units ashore. The army, now entirely ashore, begins spreading out to keep up momentum and push the offensive .
On the western side, carrier air groups pound Osaka and Kyoto relentlessly. The Royal Marines sweep Osaka clear on 9 June.
On the east, 5th Royal Marines Division is the first to move against Tokyo. Though the enemy garrison divisions are meagrely equipped and are without air support, they are firmly dug-in and refuse to give up the capital.
The first attack against Tokyo fails, with heavy casualties sustained by 5th Royal Marines. However, the invasion proceeds well on all other fronts. This view shows the situation by 11 June.
The initial attack on Tokyo did succeed in heavily wearing down the defenders: 2nd Royal Marines launches a second attack from the northern flank, and forces the exhausted garrison to retreat after a brief battle. 2nd Royal Marines captures Tokyo on 14 June.
Shortly thereafter, the Japanese sign the instrument of full and unconditional surrender on the deck of HMS Hood.
With assurances from the Emperor and the new pro-Western government that Japan’s wars of aggression are behind her, Japan is welcomed into the Allies. Most Japanese fighting units are turned over to Allied control rather than being dissolved: many of Japan’s old puppet states are left standing to carry on the fight, and the Soviet question is still looming on the horizon. But for the moment, the war in the east is done.