How did Nimitz know about Japanese intentions at the Battle of Midway?

Answer 1

The United States had broken the Japanese naval code and was able to read a significant part of the messages to give him a good idea of Japanese intentions. However, because other senior commanders believed the target identified as 'AF' in the Japanese messages could have very well meant Hawaii or the West Coast, Nimitz had to prove that the target was indeed Midway. To do this, he ordered a message sent to Midway via underwater cable instructing them to broadcast, in the clear, that their water distillation plant had broken down. Within several days, a Japanese message was intercepted advising that 'AF' was running short of fresh water.

Answer 2

Nimitz obtained crucial intelligence from U.S. codebreakers who had cracked the Japanese naval codes, specifically the JN-25 code. This allowed him to learn about the Japanese plan to attack Midway Atoll and estimate the timing and location of their attack. This intelligence played a significant role in Nimitz's decision-making and ultimately contributed to the American victory at the Battle of Midway.