Decision at Sea

by Symonds, Craig L.

  The furious repairs conducted aboard the Yorktown, and its urgent orders back to sea, were a direct consequence of one of the best-kept secrets of the war. In the basement of the Fourteenth Naval District Headquarters building at Pearl Harbor, a team of cryptanalysts, or code breakers, known to the few who were even aware of it as “Hypo” (the British phonetic designation for the letter H, referring to Hawaii), worked to penetrate the coded Japanese radio signals. Headed by Lieutenant Commander Joseph J. Rochefort, the men of Hypo spent their days (and often their nights) reading encoded Japanese messages and attempting to winkle some useful intelligence out of them. It was a task requiring patience and perseverance as well as instinct and insight.

  The Japanese operational code, known as JN-25, consisted of forty-five thousand five-digit number groups, each of which represented a word or a phrase. Thus the messages the American cryptanalysts read might look something like this:

  29845 87463 14975 27406 38591 19393

  93755 29573 57144 38048 29485 11844

  Aware that the Americans would try to penetrate the meaning of these coded numbers, the Japanese inserted random number groups throughout their messages to confuse the code breakers. The Japanese were confident that their code was sufficiently complex that no one could break it, or at least that no one could break it quickly enough to gain a tactical advantage.5

  Rochefort and his Hypo team worked frantically to crack the Japanese messages. In part their dedication derived from the nagging anxiety that if only they had been given access to the JN-25 intelligence before December 7, they might have been able to predict the Pearl Harbor attack. Instead, that information was confined to the team at Corregidor (the team known as “Cast”) and not shared with Hypo. Now that Rochefort’s team had access, they kept long hours in their sunless offices looking for repeats or patterns in the five-digit number sets. In time, they were able to “read” every fourth or fifth number group and guess at its meaning. That enabled them to make a reasonable guess at the subject of the messages. Most of those messages were routine and altogether unhelpful. The Hypo cryptanalysts might labor for hours over what looked like an important message only to determine that it was a report on the weather in Hokkaido two days before. With a sigh, they would push the message aside and start on the next one. It was not just a matter of finding familiar number groups and “translating” the message; a key element to code-breaking success was gaining an understanding of Japanese character and culture, which might offer insight into the meaning of the messages.6

  In all their work, the overriding goal of the men who worked in Hypo was to find and track the “Nagumo Force,” the six-carrier strike force of Vice Admiral Chuichi Nagumo, which had conducted the attack on Pearl Harbor on December 7 and which they referred to by its Japanese designation as the “Kido Butai.” Repeatedly they asked one another, or sometimes muttered aloud to themselves, “Where is the Kido Butai?” The answer to that question often indicated where the next Japanese blow was likely to fall.7

  Their diligence paid off. In April, Rochefort had been able to tell Nimitz about a Japanese plan to attack the allied base at Port Moresby, on the south coast of New Guinea, in time for Nimitz to send the Yorktown and the Lexington to the Coral Sea. The Japanese thrust had been turned back, though that American success had come at a heavy cost due to the loss of the Lexington and the severe damage that had been inflicted on the Yorktown. Then, even before the Battle of the Coral Sea was over, Rochefort and his team achieved another breakthrough. The Japanese, Rochefort reported, were about to launch an even bigger operation, one that involved most of their fleet, including the Kido Butai. The attack would take place in early June, and the target, Rochefort declared, was the tiny atoll of Midway.

  The number of individuals who were privy to the fact that Rochefort’s team was reading the Japanese code was very small, and not all of them were convinced that Rochefort had interpreted the messages correctly. In Washington, the head of the Code and Signal Section (Op-20-G), Captain John Redman, questioned Rochefort’s analysis. His doubt fueled the concern of the chief of naval operations, Admiral Ernest J. King, that the next Japanese operation would be against the American West Coast. If Rochefort was wrong and the Japanese hit the American mainland, there would be hell to pay. Was he absolutely sure?

  He was. Indeed, he was a little annoyed by the reluctance of some officials to accept his analysis. So to convince the skeptics, his men devised a scheme. The messages they had been tracking identified the targets of the next Japanese offensive as AK and AF. There was no dispute that AK referred to the Aleutian Islands, but to confirm the identity of AF, Rochefort’s men sent a message to the garrison at Midway by submarine cable asking that they send back a radio message in the clear—that is, uncoded—stating that their salt water evaporator had broken down and that they were running short of drinking water. Sure enough, two days after this bogus report hit the airwaves, an intercepted Japanese message reported that AF was short of drinking water. Rochefort had his smoking gun: beyond any doubt, the target of the next Japanese offensive was Midway.8

  One of America’s stepping stones across the Pacific to the Philippines, Midway was a circular coral reef embracing an enclosed lagoon. On the southern edge of that lagoon, two small sandy islands barely broke the surface of the sea; the larger island, appropriately named Sand Island, was less than two miles long. It was a barren outpost populated principally by gooney birds, whose ritual mating dance was virtually the only interesting thing on either island. Indeed, Midway had no value whatsoever but for its location. It was, quite literally, a thousand miles from anywhere: 1,100 miles to the southeast was Oahu and the American naval base at Pearl Harbor, and 1,130 miles to the southwest was Wake Island, captured by the Japanese in the early days of the war. So remote was it that there is no record of its having been “discovered” until 1859. The United States established a coaling station there two years after the Civil War, and two years after that, in 1869, the Navy began dredging a channel to provide access to the atoll’s inner lagoon, though the project ran out of money before the channel could be completed.

  Midway Atoll from the air. The island in the foreground is Eastern Island, which contained the airfield, completed only four months before the Japanese attack. Beyond it is the appropriately named Sand Island. The dredged ship channel into the central lagoon ran between the two islands, and a secondary channel can be discerned running from the lagoon to the landing dock on Eastern Island. (U.S. Navy)

  Five years after the war with Spain, in 1903, President Theodore Roosevelt placed Midway under the control of the Navy Department, and that same year the United States established a telegraph cable station on Sand Island. The outpost was further developed in the 1930s when Pan American Airlines used it as a seaplane base for its transpacific Clippers and even built a small hotel there for its passengers. In 1940, with the Second World War already under way in Europe, the Navy finally completed the channel into the central lagoon, providing a safe anchorage for deep-water ships, and the next year, only four months before the Japanese attack on Pearl Harbor, the Navy completed an airfield on the smaller island, Eastern Island. Even with these improvements, however, Midway was not a post of great strategic significance. And yet in the late spring of 1942 it became the focus of arguably the most important naval battle of the Second World War, and one of the pivotal battles of American history.9

  It was not the atoll or its airstrip that made Midway the target of the Kido Butai and much of the rest of the Imperial Japanese Navy. It was the Japanese determination to finish the job they had begun in December by luring the American carriers out from their naval base at Pearl Harbor and sinking them in deep water, where they would be beyond recovery. Midway would be the bait. The Japanese plan was to attack the American base at Midway with carrier-based airplanes, and when the American carriers sortied from Pearl Harbor to meet the challenge, they would steam into a carefully prepared trap. With the destruction of the American carrier
s, the Japanese would then be free to consolidate their conquests in the Southwest Pacific—including the Philippines and the oil-rich islands of the Dutch East Indies—and draw upon the resources of their new empire for economic self-sufficiency.10

  The news from Hypo that the Japanese planned to launch a major operation directed at the capture of Midway was an intelligence coup of the first order for the Americans, but it also created a dilemma for the commander of the U.S. Pacific Fleet, Admiral Chester Nimitz. Though he was only fifty-seven, Nimitz had snow white hair, and behind his back his young staffers took to calling him “Cottontail.” The nickname belied Nimitz’s personality, however, for there was nothing cuddly or frivolous about the American commander, who had been on the job only since the first of the year. Nimitz’s German ancestry and his Texas hill country upbringing gave him a cool, calculating, and undemonstrative demeanor. One officer who knew him well described him as “coldly impersonal.” His steady hand on the helm had helped to restore confidence after the disaster of the December 7 attack, though his inspiring competence could not completely mask the precarious situation of the American fleet in the early spring of 1942.11

  The “fleet” Nimitz had inherited consisted of a score or so of submarines and a few aircraft carriers, plus the cruisers and destroyers that had survived the Pearl Harbor attack. Nimitz himself came from the submarine community, and he immediately sent out the handful of American submarines to conduct offensive operations. It is a measure of how much the world had changed in twenty-five years that although the United States had professed horror at the German use of unrestricted submarine warfare in 1917, the first U.S. Navy operational order of the Second World War was to “begin unrestricted submarine warfare against Japan.” Early in the war, however, the U.S. submarines performed indifferently, mainly because their Mark 14 torpedoes did not work properly, though this was not discovered until later. In the meantime, sub skippers had to endure the frustration of risking their command and their lives in order to line up for a shot, and then watch while their torpedoes either failed to explode or ran too deep. When they reported these malfunctions up the chain of command, many of those in the Bureau of Ordnance who read their reports assumed unfairly that the commanding officers were making excuses for having missed the target. Not until the end of 1942 did sufficient evidence accumulate to provoke a change in torpedo design.12

  The carriers, too, had a disappointing debut. Though the Enterprise (CV-6) and the Hornet (CV-8) executed a dramatic, headline-grabbing raid on Tokyo in April by the Army Air Corps planes of Colonel James Doolittle, that raid had been designed principally to boost morale, and elsewhere there was little to cheer about. In the first five months of the war, the United States lost the Langley (CV-1), the Lexington (CV-2), and the use of the Saratoga (CV-3), which was hit and badly damaged by a Japanese submarine whose torpedoes worked only too well. That left Nimitz with only the Enterprise and Hornet plus the damaged Yorktown. All the battleships, of course, were either under repair or still at the bottom of Pearl Harbor.*

  Under these circumstances, many commanders would have been satisfied to remain on the defensive—to wait until America’s superior industrial capacity produced a new armada of ships and planes—before seeking a fight with the enemy. After all, the Japanese navy—especially the six carriers of the Nagumo Force, the Kido Butai—had been running rampant in the western Pacific since December, gobbling up new possessions and sinking any foe foolish enough to stand in their way. Nagumo’s carriers operated freely, striking at targets from Ceylon in the Indian Ocean to the Gilberts in the southern Pacific, from the Kuriles in the north to the Solomons in the south, roaming at will across a gigantic expanse of ocean without serious opposition. Only in the Coral Sea northeast of Australia had the Japanese been checked, and that had come about principally because Nimitz had trusted the information Rochefort had provided.13

  Nimitz had already decided to trust Rochefort again and to oppose the attack on Midway with everything he had. Such a decision may seem logical in retrospect, but given the disparity of forces available to each side, it was a significant gamble. If the United States lost its few remaining carriers in the fight for Midway, there would be little between Nagumo’s powerful striking force and the West Coast of the United States. Was Midway with its gooney birds worth such a risk? Nimitz thought it was. He calculated that the advance knowledge provided by Rochefort’s code breakers considerably evened the odds. Moreover, the scheduled return of the Saratoga and the arrival of the Wasp from the Atlantic would give him a backup battle force even if everything went wrong.

  But Nimitz did not expect everything to go wrong. He expected to complete emergency repairs on the Yorktown and get all three of his carriers to sea before the Japanese arrived, thereby throwing a wrench into their plans. Instead of being surprised by the Japanese, he would surprise them and send at least some of their carriers to the bottom. Nimitz was no Texas gambler; he did not throw the dice thoughtlessly. Behind those cool blue eyes was the calculating mind of a man who weighed the odds carefully and made plans accordingly. He expected to win.14

  Nimitz recalled the Hornet and Enterprise to Pearl Harbor and issued orders that the Yorktown go into immediate dry dock when it arrived to undergo emergency repairs. He scheduled a staff meeting for May 25, three days before the Yorktown’s expected arrival, to plan the details of the operation. He wanted Rochefort there to explain what he knew—or what he thought he knew. The senior brass assembled at the designated hour, but Rochefort was late. For half an hour, the commanding officer of the Pacific Fleet and his entire staff waited impatiently for a lieutenant commander. When Rochefort finally showed up, he apologized for being late and, handing Nimitz a sheaf of papers, said that the documents would explain everything. They did. Rochefort had been delayed because his team had been busy decrypting a series of recently intercepted Japanese messages dated five days earlier. As Nimitz looked them over, he saw that they not only confirmed that Midway was the target, they included “the strength of the attack and the composition of the attack forces,” and even “such things as where the Japanese carriers would be when they launched their planes, degrees and distance from Midway, and the hour and the minutes.”15

  A few skeptics worried that it might be a trick—the information was too complete. But Rochefort was certain of its genuineness. “I could not understand why there should be any doubt,” he later insisted. Nimitz agreed. The only thing he did not know was how many carriers the Japanese would have. If they sent all six carriers of the Kido Butai, the American carriers would be outnumbered two to one, even assuming the Yorktown could be patched up in time. But Rochefort predicted there would be only four carriers in the Japanese strike force. “Why not six?” Nimitz asked him. Rochefort replied that the message traffic mentioned only Carrier Divisions 1 and 2, which suggested that the two Japanese carriers that had fought in the Coral Sea—Shokaku and Zuikaku, the newest and biggest of the enemy’s carriers—had returned to Japan for repair. He did not think they would be involved in the forthcoming operation. But whether the Japanese had four carriers or six, Nimitz planned to make a fight of it regardless. After all, Midway itself would be an element of the fight—its airfield made it a kind of unsinkable aircraft carrier, which, along with the three American carriers, would make it an even fight against four Japanese carriers. And even if there were six enemy carriers, Nimitz calculated that American advance knowledge of the Japanese intention was enough to even the odds.16

  There was still the problem of who would command. As theater commander, Nimitz himself would remain at his headquarters in Pearl Harbor. To command the carrier force at sea, he needed a steady and thoughtful carrier officer, a man who knew when to take a chance and how big a chance to take. The logical man was Vice Admiral William F. “Bull” Halsey, the best-known and most aggressive of America’s carrier admirals. But Halsey had come down with a severe case of shingles, a horribly painful skin disease that would keep him hospitalized for we
eks. Devastated that he would miss the forthcoming operation, Halsey had no choice but to accept his fate, and he recommended that the commander of his cruiser-destroyer force, Rear Admiral Raymond A. Spruance, assume temporary command of the carrier division consisting of the Enterprise and Hornet. The recommendation was controversial, for Spruance was not a carrier man. He was, in the Navy’s lingo, a “black shoe” admiral: a surface warrior who had spent his career in destroyers, cruisers, and battleships. How could he be expected to know what to do in a carrier battle? Nimitz, however, thought the suggestion was inspired, for Spruance was a man very much in the Nimitz mold: quiet and undemonstrative in his behavior, but calculating and bold in his decision making.17

  Spruance would not be the senior man afloat. That responsibility fell to a rear admiral with the quintessentially American name of Frank Jack Fletcher, who not only was senior to Spruance but also had commanded the American carriers in the Battle of the Coral Sea. This was the source of another problem, however, for Fletcher’s performance in the Coral Sea had come under criticism in some quarters. Admiral King, the no-nonsense chief of naval operations in Washington, thought that Fletcher had been insufficiently aggressive in that fight and urged Nimitz to replace him. Concerned, Nimitz called Fletcher in for a conversation and quizzed him about his operations in the Coral Sea. At the end of the conversation, he decided that King’s criticism was both unfounded and unfair. Fletcher, Nimitz wrote to King, was “an excellent, seagoing, fighting naval officer” and just the man Nimitz wanted in command.18