Due to both his judgments of the state of the United States and confidence in his own fleet, Admiral Yamamoto created Operation MI, which was an extremely complex plan involving the entire Combined fleet and requiring perfect timing and execution along with the accuracy of various assumptions. Operation MI was approved by the NGS Chief Admiral Osami Nagano only after threats of Yamamoto’s resignation. The plan was set to work if America acted exactly as Japan expected, shown through the extremely late deployment of IJN submarines even though they could stay underwater, undetected for weeks. Overall, Operation MI seemed to be a political plan rather than a military operation demonstrated by the choice not to use Yamato, the rush to get it under way on Navy Day, and giving each high ranking officer a command appropriate to his rank then planning how to use them rather than creating a plan and then assigning officers. Operation MI was based on a series of assumptions: America’s oblivion to Japanese plans, …show more content…
“In attempting a surprise attack [the Japanese] were themselves surprised.” Because they had based their operations on many assumptions, specifically ones claiming America would be unwilling to fight unless provoked and that they had no knowledge of Japanese plans, that needed to be true in order to find success, the United States intercepting and correctly interpreting any part of the plan would lead to the downfall of Operation MI. Due to his confidence in the surprise Midway would be as well as his trust that Americans already had been morally defeated and physically weakened, Yamamoto allowed the Army to pursue its own plans of Operation MO, which requisitioned a third of the fleet away from Midway. US intelligence made this a fatal error. Commander Rochefort, the commander of the Combat Intelligence Office, noticed an increase in Japanese radio traffic indicating the planning of a new operation. Even though he had come to the conclusion that Japan’s intended target was Midway, he used an uncoded message in order to trick the Japanese into using its code for Midway, “AF” in order to relay the message they “intercepted.” Also, Rochefort gained knowledge of the submarine cordon, allowing forces to be deployed in advance of the cordon. Along with Rochefort’s ability to draw conclusions about Japan’s plan through decoding of more highly-encoded messages, Nimitz became