The Trap set by the US Navy at Midway(June 4-7 1942) was Admiral Nimitz call. Although Commander in Chief, United States Fleet (COMINCH) Admiral Ernest King in Washington was in constant contact with Nimitz as he made this call. We know this because it was the Pacific Fleet's intelligence officer in charge of station HYPO, Joseph Rochefort under Nimitz, and his familiarity with the Japanese J-25b code who uncovered that Midway was the Japanese fleet's next target.
Office of Chief Of Naval Operations Signals Intelligence, OP-20-G based in Washington D.C. and station CAST then based in Australia; disagreed with Rocheford and Nimitz and thought the attack's target was probably the Aleutian Islands. possibly Port Moresby in Papua New Guinea, or even the west coast of the United States. Station HYPO then confirmed Midway was the target by requesting Midway to send an un-encrypted message about their desalination plant; which the Japanese intercepted and rebroadcast encoded. Thus verifying the identity of the disputed location AF was Midway.
Quote Given in T.E.D's answer
A persistent Midway myth is that the intelligence picture was so perfect, like reading the actual Japanese operation order, that even the day and time of the initial attack on Midway was known well beforehand. In truth, Nimitz worked only from a broad outline of Japanese intentions and partial order of battle, absolutely invaluable as they were.
The Midway intelligence was actually very specific and incredible accurate. The date and time of the attack, the degrees from Midway of the Japanese Carriers would approach from, and their distance from Midway was off by: "five minutes, five degrees, and five miles out". ( That's the difference between the intelligence officers statement before the battle began and the Japanese's Carrier's location after the initial attack on Midway ).
The Battle of Midway
Only an hour earlier Nimitz had asked Layton (his Intelligence officer) to give him a specific prediction of when and where the Japanese carriers would be first spotted. Layton swallowed hard and hazarded 0600, from the northwest at a bearing of 325 degrees, at a distance 175 miles from Midway. When Nimitz received the PBY's report in his operations room he could not resist tweaking his intelligence officer; turning to Layton he dryly commented, "Well, you were only five minutes, five degrees, and five miles out."
Codebreakers Set a Trap to Confirm Japanese Attack
By the end of May, Navy cryptanalysts had figured out more details about Yamamoto’s plans, including almost the entire order of battle of the Imperial Navy. With this information, Nimitz was able to plot a strategy that would take the Japanese by surprise, assembling three U.S. aircraft carriers at a spot some 300 miles north of Midway, which they called “Point Luck.”
Order of Battle
In modern use, the order of battle of an armed force participating in a military operation or campaign shows
- the hierarchical organization,
- command structure,
- disposition of personnel,
- equipment of units and formations of the armed force.