He leaned back, closed his eyes, and listened….
Another man was listening, sitting in a cellar deep beneath the administration room at Pearl Harbor. The building above had been gutted by fire, but the cellar housing Station HYPO had survived. In the last three months the rubble had been cleared, new construction started, and it was nearly complete. Yet all the while, the station, a branch of OP-20-G Naval Intelligence section in Washington DC, had continued to operate. Their mission was signals intelligence and decryption, and they had some very talented minds there, including one Lieutenant Commander Joseph Rochefort, who had joined the Navy while still in high school in 1918. A man with a complex mind, much like Alan Turing, Rochefort delighted in solving crossword puzzles, or analyzing the possibilities of card games, particularly bridge. It was the kind of mind that was tailor made for code breaking, and that is what Rochefort did.
Station HYPO, sometimes called Fleet Radio Unit Pacific (FRUPAC), had a sister station labeled FRUMEL in Melbourne, and together they had been listening… listening…. All the real decryption work was piling up at those two sites now, as Hong Kong was gone, along with Batavia, and Corregidor. They took the burden, and worked hard, and had some real success in breaking the Japanese JN-25B naval code. Now it was telling them some very dangerous things.
Orders were afoot, signals traffic up all across the bands, and ships were on the move. This made for late hours and long shifts at HYPO, but slowly, a rather ominous picture was being painted by the signals traffic. Lieutenant Commander Jasper Holmes had been very methodical, working from the assumption that something was up for the Central Pacific. The Americans had learned that the movement and deployment of the Japanese carriers was the first thing to look for, and they had clearly identified a carrier with a name ending in “kaku” ordered to Truk. Only two ships had that suffix, and they were both in the same Carrier Division, Number 5, Japan’s newest and most modern carriers.
Holmes came up to Rochefort’s desk, the green eye shades the men used to protect their eyes from the endless overhead fluorescent lighting now perched high on his forehead. He had caught a few hours sleep on a cot by the wall, then was up early to see if anything new had come in. He was very pleasantly surprised. Rochefort was sitting behind a wall of stacked file folders and reports, half way through a cup of coffee. A veil of pipe smoke always seemed to surround his desk, like fog hugging the ragged shore of some isolated Pacific island.
“If Div Five has moved to Truk,” said Rochefort, “what makes you think they’re heading for the Central Pacific?”
“Truk is the center of the wheel,” said Holmes. “From there they could head south into the Solomons, or southwest towards the Coral Sea. There are good objectives there. We know they want Port Moresby. That’s why Fletcher has Saratoga and Yorktown off Fiji right now, ready to move west into the Coral Sea. They could save him the trouble and also head right for Fiji from Truk, and that has a lot of folks worried. So I decided to play a little game.”
“A game?”
“Right. We know the call names of several objectives, so I put out some traffic on the radio last week, just an innocuous little laundry list of maintenance trouble, and I sent it in the clear. I had the report say they had trouble with the water condenser on Midway, and needed lubricating oil for a crane at Suva Bay—two nice fat objectives the Japs might be eyeing now. And guess what. We picked up a message just yesterday. The Japs took my bait, hook, line, and sinker!” His smile drove the weariness from the lines of his face.
“What do you mean?”
“A.F. sir, that was one of the call signs attached to an objective point. We picked up a message repeating that A.F. had trouble with its water condenser. I decoded it myself. So A.F. has to be Midway, and by elimination, we figured out what Fiji must be. No action there, but everything else seems to be pointing to Midway. We even picked up movement order for fleet unit 8 O K.I. We know what that is sir, because the Japs always pair sister ships, and 9 O K.I. was clearly ordered to Kwajalein right after the attack on Pearl. That was Kaga, the ship Halsey busted up in that first engagement. So 8 O K.I. has to be the Akagi, and they want it ready for a move to support the operations for A.F—for Midway.” He folded his arms, a smug look of satisfaction on his face.
“Midway,” said Rochefort. “Why the Central Pacific?”
“Unfinished business,” said Holmes. “If they can knock off Midway, then we lose that important watch on all that turf out there.”
“Or maybe something else,” said Rochefort. “Know thine enemy, Holmes. We know Yamamoto has been wanting to lock horns with our carriers for some time. That’s his guiding principle—seek out a decisive engagement. That’s why he hit us at Pearl.”
“Right. Well I think they’re going to sortie into the central Pacific, and take a pot shot at Midway. They know Halsey has been nipping at the Marianas, and that stunt Doolittle pulled off must have reddened quite a few faces in the navy over there. If they had Midway, they could put seaplanes there and we would have never been able to pull that raid off. It’s a big blind spot for them out there, and possession of Midway solves that problem nicely.”
“How sure are you about this?”
“Well, we’ve also got Nagumo’s call sign—that was 8 E YU, before they changed it to 8 YU NA. We have sixteen readings where that call sign is paired with the 8 O K.I. for the Akagi. So that has to be the flagship for this operation, and they’re moving it to Truk to link up with Carrier Division 5. That’ll give them at least three big flattops ready to move in five days. And there’s more, we’ve got the handle for one of their fleet replenishment ships, Kyukuto Maru. It’s the flagship for the tanker fleet. It’s got orders to proceed to support this operation A.F. too.”
“Have you run this by anyone else?”
“Rear Admiral Layton, and he thinks it’s good. He wanted me to get this to you right away.”
“What about Tommy Dyer?”
“I’ll get to him next. I wanted you to see this first hand.”
Rochefort thought for a moment. “Let me look over those traffic decrypts. A lot is riding on this, and we need to get our ducks lined up perfectly. Did you put these latest ship movements up on the big board yet?”
Holmes was in charge of tracking all ship movements, and he had rigged out a large plotting board on the wall where he would update positions on all the key players in this complex game of chess in the Pacific.
“Find anything else we’ve got on A.F. See if you can cross reference anything. I think the file is under that box there.” Rochefort pointed to a clutter of boxes and stacks of paperwork surrounding one of the other desks like a coral reef. Each man sat on his private little island, with mountains of file folders and jungles of paperwork. They never did set up any proper filing system, but there was a hidden order to the apparent chaos, and just like that, Rochefort could point to a box on the floor and know the A.F. ship track file was tucked away beneath it. Many of the men there had near photographic memory for things like that. To them the clutter was like a road map or navigation chart, and they could read it unerringly.
“So you figure this is what they called off the Indian Ocean thing for?” Rochefort scratched his head.