Preparations for Midway

In the last week of May 1942 fleet movements began in the Pacific which ten days later led to one of the most important naval battles in history. On 25 May according to some Japanese studies, or a day later according to others, Rear Admiral Kakuji Kakuta’s force of two aircraft carriers left the base of Ōminato at the northern tip of Honshu to strike at the American bases in the Aleutians. On 27 May, the anniversary of the victory at Tsushima, four carriers under Vice Admiral Chūichi Nagumo sailed from the anchorage of Hashirajima in Hiroshima Bay, heading for Midway atoll. The same day the carrier Yorktown, damaged in the Coral Sea, entered Pearl Harbor (PL), and on 30 May, after repairs lasting less than three days, she put to sea again to join the force built around Enterprise and Hornet.

War chronologies split these events into three separate entries: on 25 May the Japanese sent a “diversionary force” to the Aleutians, on 27 May Yorktown arrived at Pearl Harbor, and on 30 May she sailed to join Enterprise. All three are parts of a single story: preparations in which one side knew the other’s plan in detail, while the other did not know it.

Yamamoto’s plan

Admiral Isoroku Yamamoto, commander of the Combined Fleet, had been looking since the beginning of 1942 for a way to destroy the American carriers that had escaped the blow at Pearl Harbor. He chose Midway, a small atoll at the western end of the Hawaiian chain, some 2,100 kilometres from Oʻahu. The atoll itself was of no great value to Japan, but Yamamoto reckoned that the Americans, regarding it as an outpost of Hawaii, would have to defend it and would bring the rest of their fleet out to sea. Once the atoll had been taken, the Japanese carriers and the battleships following them were to destroy that fleet in a decisive battle.

The Naval General Staff under Admiral Osami Nagano preferred operations in the South Pacific, against New Caledonia, Fiji and Samoa, which were to cut Australia off from the United States. At the beginning of April it gave way when Yamamoto threatened to resign, and the Doolittle Raid of 18 April silenced the remaining objections: if American carriers could approach Tokyo, they had to be destroyed. On 5 May Imperial General Headquarters Navy Order No. 18 instructed the Combined Fleet, in co-operation with the army, to seize Midway and key points in the western Aleutians. The operation against the atoll was code-named MI, the Aleutian operation AL.

The plan was vast and complicated, in keeping with Japanese doctrine. The strike was to be delivered by Nagumo’s Kidō Butai with the carriers Akagi, Kaga, Sōryū and Hiryū, which on the day of sailing carried some 250 aircraft. Behind it came Vice Admiral Nobutake Kondō’s invasion force with transports from Saipan carrying about five thousand army troops and naval infantry, and, several hundred miles to the rear, Yamamoto’s own main body with the super-battleship Yamato. In the north Vice Admiral Boshirō Hosogaya’s Northern Force was to operate. Before the battle a line of submarines was to watch the route from Hawaii, and flying boats – in a repeat of Operation K – were to take a look at Pearl Harbor. The Japanese assumed that the Americans had at most two serviceable carriers in the Pacific, Enterprise and Hornet, since they believed Yorktown had been sunk in the Coral Sea.

The plan had weaknesses that were noticed even at the time. In war games aboard Yamato at the beginning of May it turned out that land-based American aircraft could sink Japanese carriers; Yamamoto’s chief of staff, Rear Admiral Matome Ugaki, reduced those losses by an arbitrary umpire’s ruling. After the Battle of the Coral Sea the two most modern carriers, Shōkaku and Zuikaku, dropped out of the plan: the first was damaged, the second had lost too many aircrew. The date, however, was kept.

The Aleutians: diversion or separate objective?

On 25 or 26 May (Japanese sources give both dates) Kakuta’s 2nd Carrier Striking Force left Ōminato with the light carrier Ryūjō and Jun’yō, commissioned only on 3 May, two heavy cruisers and destroyers. On 3 June it was to bomb the naval base at Dutch Harbor on Unalaska Island. In the following days the landing forces sailed that were to seize the islands of Kiska and Attu (on 28 and 29 May according to Japanese studies) and, originally, Adak as well.

The term “diversionary force” matches the picture in which most historians presented the operation for decades: the attack on the Aleutians was supposedly meant to draw the American fleet north before Nagumo struck at Midway. More recent research, above all by Jonathan Parshall and Anthony Tully, based on Japanese documents, undermines that picture. Under the original plan both strikes were to take place simultaneously; the attack on Dutch Harbor preceded the attack on Midway by a day only because Nagumo’s force left Japan a day late. Over such distances the fleet from Pearl Harbor could not in any case have reached the Aleutians and returned in time. Operation AL had, rather, objectives of its own: it was the price the navy paid the army for its participation in Operation MI, and the seizure of the western Aleutians was to block the American route from Alaska towards the Kurils and Japan and to cover the northern flank. In the process it dispersed forces that could have strengthened the blow against Midway, including two carriers.

The Americans knew about Operation AL from intercepted signals. Admiral Chester Nimitz, commander of the Pacific Fleet, sent Rear Admiral Robert Theobald’s force of cruisers and destroyers to Alaska, but did not send a single carrier there. He was saving them all for Midway.

“AF is short of water”

The Americans’ advantage lay in the fact that they were reading part of the Japanese traffic. Since the beginning of the year the cryptanalysts of Station Hypo at Pearl Harbor, headed by Commander Joseph Rochefort, had been breaking an ever larger part of the Japanese fleet’s operational code, known as JN-25; the same work had given the Americans their strategic victory in the Coral Sea. From April onwards a target designated by the letters “AF” kept recurring in the signals. Rochefort and the Pacific Fleet’s intelligence officer, Commander Edwin Layton, were convinced that it meant Midway, but in Washington some analysts suspected Hawaii, the Aleutians or even the US West Coast.

The question was settled by a ruse usually attributed to Lieutenant Wilfred Holmes of Rochefort’s team. Around 19–20 May the Midway garrison, having received instructions by undersea cable, which the Japanese could not intercept, sent a message in plain language reporting that the atoll’s water distillation plant had broken down. Soon afterwards Hypo read a Japanese signal stating that “AF is short of water”. From then on Nimitz had no doubts. In the following days the cryptanalysts also broke the Japanese system for encoding dates and established that the attack would come at the beginning of June. Layton even predicted that the Japanese carriers would be sighted on the morning of 4 June north-west of Midway, about 175 miles from the atoll; he was out, as it later turned out, by a few miles and a few minutes.

The Japanese were about to change their code books. The change, originally planned for 1 April and then for 1 May, had been postponed because of the difficulty of distributing the new tables to scattered ships and bases; the new version of the code came into force only at the end of May (studies give 24 or 28 May). A few days before the battle the Americans stopped reading current traffic, but they already knew the most important things: the target, the date and, in broad outline, the enemy’s strength.

Nimitz gathers his forces

Nimitz had little at his disposal. After the loss of Lexington, and with Saratoga under repair on the West Coast, he was left with Enterprise and Hornet, which returned from the South Pacific on 26 May, and the damaged Yorktown. The same day the commander of Task Force 16, Vice Admiral William Halsey, was taken to hospital with a severe, debilitating skin inflammation. As his successor he recommended Rear Admiral Raymond Spruance, commander of his force’s cruisers, a calm and precise officer, though not an aviator. Nimitz agreed. Spruance took over Halsey’s staff and on 28 May led Enterprise and Hornet out of Pearl Harbor.

At the same time the atoll itself was being strengthened. Nimitz had visited Midway as early as 2 May and asked its commanders what they needed. Throughout May anti-aircraft guns, Marine units, light tanks and aircraft arrived there: Marine fighters and dive-bombers, Catalina flying boats, Army Air Forces B-17 and B-26 bombers, and six new Avenger torpedo bombers. On the day of the battle there were some 120 aircraft on the atoll, most of them, however, obsolete or flown by inexperienced crews. The Pacific Fleet’s submarines were stationed on the approaches to Midway.

On 27 May Nimitz’s staff issued the operation plan. The carriers were to wait north-east of Midway, at a position named “Point Luck”, beyond the range of Japanese reconnaissance, and strike the Japanese carriers from the flank when these attacked the atoll. In his written instructions to his commanders Nimitz ordered them to be governed by “the principle of calculated risk”: not to expose their carriers to attack by superior forces unless they could thereby inflict greater losses on the enemy.

Yorktown’s three days

Yorktown entered Pearl Harbor on the afternoon of 27 May, trailing a slick of fuel from her ruptured tanks. The bomb that on 8 May had pierced four decks, and the near misses that had strained her plating, had caused serious damage. According to the popular version, engineers estimated the repairs at three months in a West Coast yard; according to the ship’s official history, inspectors from the Pearl Harbor Navy Yard judged that at least two weeks were needed. Nimitz demanded that the ship be ready in three days.

The next morning, 28 May, the carrier was moved into Dry Dock No. 1. Nimitz, in rubber boots, inspected the hull in person. It turned out that the aircraft lifts were working and that the flight deck could be patched. For two days and nights some 1,400 dockyard workers laboured on her, supported by teams from the repair ship Vestal, herself damaged on 7 December 1941. Whole sections of frames were cut out and replaced, the plating and deck were patched, and the lights in the dry dock burned through the night. A full repair was not carried out: some of the damaged boilers were not repaired, nor was the full watertightness of the compartments restored. The ship had to last a few weeks of operations and no more. On 29 May Yorktown left the dock, and some of the work was finished at sea.

Her air group, bled white in the Coral Sea, also had to be rebuilt. It was filled out with squadrons from Saratoga: the dive-bomber squadron VB-3, torpedo squadron VT-3 and Lieutenant Commander John Thach’s fighter squadron VF-3, in which a dozen or so pilots of Yorktown’s former squadron also flew. Many of the airmen knew neither one another nor the ship. On 30 May Thach’s executive officer, Lieutenant Commander Donald Lovelace, was killed in an accident while landing on board.

On the morning of 30 May Yorktown, as flagship of Rear Admiral Frank Jack Fletcher’s Task Force 17, left Pearl Harbor escorted by two heavy cruisers and several destroyers. She headed to meet Spruance’s force with Enterprise and Hornet; the rendezvous took place on 2 June near Point Luck. As the senior officer, Fletcher then assumed tactical command of both forces. The three American carriers carried some 230 aircraft, and with the aircraft on Midway the Americans almost matched Nagumo in the air.

The Japanese at sea

Meanwhile the Japanese fleet was steaming east. On 27 May Nagumo’s force left Hashirajima, on 28 May the transports with the landing troops sailed from Saipan under the cover of Rear Admiral Raizō Tanaka, and on 29 May Yamamoto’s battleships and Kondō’s forces put to sea. Operations MI and AL involved, by various counts, from about 150 to more than 200 warships and auxiliaries in all – the largest fleet Japan sent to sea in this war.

Reconnaissance, however, failed from the start. The submarine line that was to detect American ships on the route from Hawaii took up its positions late, after the American forces had already passed it. The repeat of Operation K never took place: on 30 May the submarine I-123, which was to refuel the flying boats at French Frigate Shoals, found American ships there, and on 1 June the flight was called off. In the last days of May Japanese radio monitoring picked up increased radio traffic and submarine activity around Hawaii, but Yamamoto, sailing under radio silence, did not pass these signs on to Nagumo, assuming that he had received them from Tokyo. Nagumo therefore sailed towards Midway convinced that the American carriers were far away.

Significance

The preparations of the last days of May decided the course of the Battle of Midway. On 3 June Kakuta’s aircraft bombed Dutch Harbor, and on 6 and 7 June the Japanese landed unopposed on Kiska and Attu, the only territories of the United States in North America to be occupied in this war; retaking Attu cost the Americans a hard battle in May 1943. On 4 June American dive-bombers destroyed Akagi, Kaga and Sōryū, and in the afternoon Hiryū. Aircraft from Yorktown sank Sōryū and helped to destroy Hiryū, while the carrier herself, hit by airmen from Hiryū and finished off by a submarine, sank on 7 June. Had she not been repaired in three days, the Americans would have had two carriers at Midway instead of three.

The Battle of Midway is regarded as the turning point of the war in the Pacific. Japan lost four of its six large carriers and the strategic initiative, and its industry was unable to make good the losses as quickly as America’s. This was decided to a large extent in the weeks before the battle: by the work of the cryptanalysts, by Nimitz’s decision to stake all his carriers on a single throw, and by the efforts of the dockyard workers at Pearl Harbor, set against Yamamoto’s dispersed plan built on false assumptions.