It was on 5 May that Yamamoto, having run out of other lands to conquer, finally received the official go-ahead for the occupation of Midway.

It had been a hard-sell for Yamamoto. He had to agree to occupy the Aleutians, too, and then, a few weeks later, to go after Samoa and Fiji.

No U.S. Navy intercept stations copied Yamamoto’s first dispatch placing the MI (for Midway) operation on a high priority time schedule. But other messages soon became quite interesting — – messages ordering various ships to do this and that, to proceed to here and to there, arriving at places we could generally identify by dates we could not ascertain. Washington and the Dungeon might disagree as to dates by as much as ten days, and sometimes more. Worse yet, Washington said the move would be toward Fiji – Samoa – New Caledonia, while the Dungeon was convinced that everything was pointing to Midway (and the Aleutians).

By 14 May Rochefort via Layton had convinced Admiral Nimitz that the Japanese were going to move against Midway, while Admiral King “wished” that HORNET and ENTERPRISE protect the Australian life line. And that was far from Hawaii and Midway.

02
Admiral Raymond A. Spruance

Japanese wartime histories show that on 15 May, radio traffic from Pearl Harbor suddenly increased tremendously and remained high — particularly in volume of high priority traffic. That state of affairs continued on and on and on—-.

It was on that 15 May that Nimitz went against the “wishes” of King and started calling his carriers back to Pearl in preparation to defend Midway. Brave, brave Admiral Nimitz. Going against King’s “wishes”. No man could ever have trusted the Dungeon more! Thank Heaven for Admiral Chester W. Nimitz!

While the Dungeon (Rochefort, Finnegan, Lasswell, and Layton) were crying “MIDWAY!! MIDWAY!” Washington was stoutly maintaining that we were “WRONG! WRONG! WRONG!” It was Oahu, or the West Coast, or even Fiji – Samoa – New Caledonia. The other point of disagreement was the time schedule. Rochefort found solidly verifiable arguments that Midway was to be in early June; Washington still insisted that date was much too early.

By 20 May Rochefort had hard evidence that the move was to be against Midway with a diversionary raid and occupation was taking place in the Aleutians.

By 26 May HORNET and ENTERPRISE were back in Pearl. They would have to leave by the 29th. YORKTOWN, damaged, made it back on the 27th. It had to be band-aided and got out, mostly with new air units, on 30 May! Poor, over-worked, battered, hard pressed YORKTOWN!

Dates were still uncertain and disagreement was high. Then, on 26-27 May, two of the Dungeon’s greats, Joe Finnegan and “Ham” Wright, using the scantiest material ever to produce world – shaking results, solved the date-cipher “garble” table used to encipher dates inside the JN-25 system.

The Aleutians would be attacked on 3 June — a diversionary raid. Carriers would attack (start softening up) Midway on 4 June. Midway would be occupied on 7 June.

AND THESE DATES NOW WERE DEFINITE! THE DUNGEON DID IT! And Nimitz’s hurried schedule built on Dungeon’s earlier and less certain estimates, would hold just fine!

And on 27 May, the Japanese Navy, after almost two months of trying to do so earlier, changed both the codebook and the cipher of JN-25. We knew this would happen. Thank Heaven their hopes to change the system as early as 1 April had proved to be impossible.

So now all of our feverish activity came to a sudden halt. We mostly sat on our thumbs and waited. The Japanese now had a horrifying seven days — one entire week — in which, unknown to us, to change their plans and ruin everything, or even to cancel the entire operation. In either case they would make monkeys of us in the Dungeon and a martyr of Admiral Nimitz.

We in the Dungeon waited — that was all we could do- anxiously, hopefully, nervously,

11
PBY Patrol Plane

fretfully, anticipatingly -until! Until early on the morning of 3 June Ensign Jack Reid, flying a PBY patrol plane from Midway, found the slow-moving Occupation Force where the Rochefort-Layton duo said it would be sighted at that time. Operation MI was still on! Joe Rochefort, Eddie Layton, Joe Finnegan, Red Lasswell, Tom Dyer, Ham Wright, Tom Huckins, John Williams, Jack Holtwick, Jasper Holmes, Allyn Cole, Banks Holcomb, John Roenigk, Art Benedict, Gil Slonim, and Forrest Biard all could now relax and smile again, could hope, could chew their nails, could close their eyes and pray for our forces, out men, our flyers, and our ships and planes and submarines at sea, in the air, and on land at Midway and in the Aleutians.

Our prayers, there, too were answered. When the final results were known we could hardly be described as elated. More appropriately, perhaps, we were thankful. How very thankful! We were emotionally exhausted.

I am as proud today as I was on that night of 4 June 1942 –Our Dungeon group had done its job superbly. And we won –thank God — but only by the very skin of our teeth. A cliffhanger? Was there ever a higher, more terrifying precipice?

17
Admiral Chester W.Nimitz

No one not in that Dungeon group can ever know, can ever feel, can ever appreciate how superhumanly magnificent our giants and their helpers were.

And Layton, and Admiral Nimitz, and Admiral Spruance, and those who fought and lived and especially those who fought and died at AF.

THE CODE BREAKING MIRACLE THAT MADE THE MIRACLE AT MIDWAY POSSIBLE.

It was a heroic time. It was not the doing of any one man or any one of our navy’s three code-breaking stations; it required the collaboration of many persons in different but closely related and highly dependent fields, though from first to last the deeply creative and subtle and critical spirit of Joe Rochefort at our Pearl Harbor station guided, deepened, and finally transmuted the enterprise. It was a period of impatient work, of crucial experimentation and daring actions, of many false starts and many untenable conjectures. It was a time of earnest communication and hurried conferences, of debate, criticism, and brilliant analytical improvisations.

For those of us who participated, it was a time of creation; there was terror as well as exaltation in our new insight. It will probably not be recorded very completely as history. As history, its recreation would call for an art as high as the story of Oedipus or the story of Cromwell, yet in a realm of action so remote from our common experience that it is unlikely to be known by any poet or historian.

Source: http://www.usspennsylvania.com/TheDungeon.htm