Operations Olympic and Cornet

How long did the US expect the Japanese to fight on before throwing in the towel? And was the invasion ever war gamed out like Sea Lion was?
 
The defeat of Japan was expected to be eighteen months after the defeat of Germany. Call it Nov-Dec '46.

As for war games, there never was a Sixth Army war game for OLYMPIC, either before the war ended or after. V Amphibious Corps did war-game their intended role in OLYMPIC, with their Japanese counterparts in the 40th Army (four divisions and three independent brigades) as they were the Kyushu occupation forces after the surrender. The Marines found a number of surprises: first, the Japanese expected the Marine beaches to be further north than where they planned to come ashore (Kushikino). Those beaches were held by two battalions, and would have been hit by two Marine Regimental Landing Teams each. The Japanese 303rd ID would have tried to counterattack, but they were a coastal-defense division and could hardly maneuver. The Marines expected enemy reinforcements within 36 hours. They were surprised that it would have taken, due to poor roads, Japanese shortages of fuel and motor vehicles, and the expected presence of American air power, nine days to reinforce the defenders. The game had the Marines taking Kagoshima City (their main objective in OLYMPIC) by X+30, and Sendai, their northernmost objective by X+48.
 
Not sure: the material on the war game doesn't mention projected casualties for V Amphibious Corps. Japanese casualties, though, would have been extreme.
 
Not sure: the material on the war game doesn't mention projected casualties for V Amphibious Corps. Japanese casualties, though, would have been extreme.

Ok. Just wondered if they may have speculated to compare what the first planners thought US casualties would be.
 
In the SPI game of the same name it pays the solo player to land north of the "historical" beaches, ie where the Japanese expected the US to do so. Initially casualties are higher (the player loses points every time they take casualties so they have an incentive to minimise them). However, they can then trap a lot of Japanese troops to the south of them, cut their supplies off then kill them with reduced US losses.

For positive victory points the Americans score for captured cities and towns as well as how much of territory they control south of their objective line. Experience has shown me that it is better to land as far north as Tsuno Beach then drive westwards rather than land in the south and bull north. It is not that a player can not reach the line from the latter landing zone. It is just that all things equal the margin of victory tends to be higher with a Tsuno landing.

In the game Japanese casualties are not recorded. However, every unit in the south and a fair few that flow from the north get totally eliminated. In a "good" game the American take about 50,000. In a "bad" game, a lot worse.
 
At Tusno, that may have worked. However, at Ariake Bay and Kushikino, there really was no other choice. You want to open Kagoshima Bay and get the airfields around Kanoya? Land where XI Corps and VAC were supposed to in the OLYMPIC plan.
 
At Tusno, that may have worked. However, at Ariake Bay and Kushikino, there really was no other choice. You want to open Kagoshima Bay and get the airfields around Kanoya? Land where XI Corps and VAC were supposed to in the OLYMPIC plan.
In the game you land 9 marine regiments on the middle of Sendai Beach, 9 army regiments on Tsuno Beach with the right flank on the edge of the objective line and 9 more on the north end of Miyazaki Beach. The marines bull their way into Kagoshima (it is a valuable objective) whilst the army expand their enclave.

There are 15 regiments of reinforcements of which can land on a new beach and 6 through an existing beach head. Unless you get slaughtered by Tokku attacks or screw things up victory is usually within your grasp.
 
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