Plan MI: Yamamoto’s Gamble and Nimitz’s Answer

Yorktown in Dry Dock No. 1 at the Pearl Harbor Navy Yard, 29 May 1942, during the emergency repair of her Coral Sea damage; she sailed for Midway the next morning. U.S. Navy photograph 80-G-13065, National Archives, public domain, via Wikimedia Commons.

The Battle of Midway · Chapter 2 of 9

Plan MI: Yamamoto’s Gamble and Nimitz’s Answer

Yamamoto built a plan to lure the Pacific Fleet to its destruction; Nimitz, reading the plan in advance, sent his last three carriers to wait on its flank.

April – 3 June 1942Tokyo · Hashirajima · Saipan · Pearl Harbor · French Frigate Shoals · Point Luck~25 min read

By the spring of 1942 the Imperial Japanese Navy had done almost everything it set out to do. In five months it had crippled the U.S. battle line at Pearl Harbor, covered the conquest of Malaya, the Philippines and the Netherlands East Indies, and sent its carrier striking force as far west as Ceylon. What it had not done was destroy the American aircraft carriers, which had been at sea on 7 December 1941 and had spent the months since raiding the edges of the new Japanese perimeter. The question of what to do next divided the Navy’s own leadership, and the answer that emerged in April and May 1942 was the operation the Japanese called MI: the seizure of Midway Atoll, 1,100 nautical miles northwest of Pearl Harbor, as bait to bring the U.S. Pacific Fleet out to be destroyed.

This chapter is about the plan and the forces on both sides before the first shot of 3 June. It follows Admiral Isoroku Yamamoto’s Combined Fleet from the strategic debate in Tokyo to the sortie from the Inland Sea, and Admiral Chester W. Nimitz’s Pacific Fleet from the first decrypts to the rendezvous northeast of Midway that the Americans called Point Luck. The codebreaking that made Nimitz’s response possible is told in Chapter 1; the defenses of the atoll itself are in Chapter 3.

Two simplifications from the older literature need to be set aside at the start. The first is that the Japanese came to Midway with overwhelming strength at the point of contact. They had overwhelming strength in total, but the plan spread it across the North and Central Pacific in groups that could not support one another, and the force that actually met the American carriers was roughly their equal in aircraft. The second is that the Aleutian operation was a feint meant to draw the U.S. fleet north. That reading appeared in the U.S. Navy’s own 1943 narrative, but later research on the Japanese side has largely discarded it.

Where the sources disagree on numbers, dates or the meaning of a decision, the disagreement is noted. Japanese planning is reconstructed mainly from postwar accounts: the 1945 interrogations by the U.S. Strategic Bombing Survey, the memoir of Mitsuo Fuchida and Masatake Okumiya (1955), and the modern reassessment by Jonathan Parshall and Anthony Tully in Shattered Sword (2005), which drew on Japanese official histories and records. The U.S. side rests on contemporary documents, particularly the Office of Naval Intelligence Combat Narrative issued in 1943, and on John Lundstrom’s and Craig Symonds’s later studies.

What next? The argument in Tokyo

Japanese naval planning in early 1942 had two centers that did not always agree. The Naval General Staff in Tokyo, under Admiral Osami Nagano, was formally responsible for strategy. The Combined Fleet, Yamamoto’s seagoing command, was responsible for operations but had in practice been setting the agenda since Yamamoto forced the Pearl Harbor plan through in 1941. Once the first-phase conquests were secured, the two staffs proposed different second phases.

The Naval General Staff’s preferred course pointed south and east. Its planners, among them Rear Admiral Shigeru Fukudome, chief of the operations section, and Commander Tatsukichi Miyo, wanted to extend the perimeter toward New Caledonia, Fiji and Samoa to cut the sea route between the United States and Australia. The scheme, known as the FS operation, would isolate Australia as a base for an Allied counteroffensive. The Army, wary of committing more divisions while it was engaged in China and watching the Soviet frontier, was cool toward anything that required large ground forces, including a proposal to invade Australia itself.

Yamamoto’s staff, led by his senior staff officer, Captain Kameto Kuroshima, argued for the Central Pacific instead. Their reasoning started from the American carriers. As long as those carriers existed, they could raid Japanese bases and, eventually, the home islands; Japan’s industrial base could not match the American building program, so the Pacific Fleet had to be brought to battle and destroyed in 1942, before new U.S. construction arrived. An attack on Midway, close enough to Hawaii that the Americans would have to respond, was the means of forcing that battle. Possession of the atoll would also extend Japanese air search eastward.

The two staffs met in Tokyo in early April 1942. Yamamoto’s representative, Commander Yasuji Watanabe, presented the Midway concept and met resistance on familiar grounds: Midway was too close to Hawaii to hold, too far from Japan to supply, and of doubtful value even if taken. Postwar accounts relayed by Fuchida and later historians agree that the opposition ended when Yamamoto made it clear, through Watanabe, that he would resign if the plan were rejected. The Naval General Staff gave way around 5 April.

Approval did not end the competition between plans. The Naval General Staff kept the southern operations alive, and the sequence that emerged had three parts: Operation MO, the seizure of Port Moresby and Tulagi in early May, which led to the Battle of the Coral Sea; Operation MI against Midway, combined with Operation AL in the Aleutians, in early June; and the FS operation afterward. This stacking of objectives meant that the Navy’s carrier strength was divided between the south and the Central Pacific in the weeks before Midway, a decision with direct consequences described below.

Sixteen bombers over Tokyo

On 18 April 1942, sixteen Army B-25 bombers under Lieutenant Colonel James H. Doolittle took off from the carrier Hornet, escorted by Vice Admiral William F. Halsey’s Task Force 16 with the Enterprise, and bombed Tokyo and other cities on Honshu. The physical damage was small. The effect on Japanese planning was large. The raid showed that American carriers could reach the home islands and that the picket line of small patrol craft east of Japan could not prevent it. For a navy whose central mission was the protection of the Emperor and the homeland, the raid was a humiliation, and it removed any remaining argument against Yamamoto’s plan.

The 1943 Combat Narrative, written with no access to Japanese records, already linked the two events: its foreword stated that the Naval General Staff decided to attack Midway after the raid. Postwar evidence shows the decision had been taken in principle in early April, before the raid, but that the raid settled the timing and the priority. On 5 May 1942, according to Fuchida’s account, Admiral Nagano issued Imperial General Headquarters Navy Order No. 18, directing the Combined Fleet to occupy Midway and points in the western Aleutians in cooperation with the Army.

Confusion about the raid persisted even among senior Japanese officers. Interrogated in Tokyo by the U.S. Strategic Bombing Survey on 15 October 1945, Captain Watanabe told Captain C. Shands that the Midway occupation was planned after the raid and gave a reason that does not match what the Japanese had known in April 1942 about the carriers’ role: “We thought the planes came from MIDWAY.” The statement is a later recollection, recorded through an interpreter, and is better read as evidence of how Midway had come to be seen as the eastern gap in Japan’s defenses than as an accurate account of 1942 intelligence. Watanabe also said the atoll was to become a base for long-range search aircraft and submarines to guard against further raids.

Plan MI and Plan AL

As finally written, the plan had two linked operations. In the north, Operation AL called for carrier air strikes on the U.S. base at Dutch Harbor in the eastern Aleutians and the occupation of Attu, Kiska and (initially) Adak in the western Aleutians. In the Central Pacific, Operation MI called for Vice Admiral Chuichi Nagumo’s First Air Fleet, the carrier striking force known as the Kido Butai, to approach Midway from the northwest, destroy the atoll’s aircraft and defenses, and cover landings by about 5,000 troops of the Navy’s special naval landing forces and an Army detachment under Colonel Kiyonao Ichiki. Once the U.S. Pacific Fleet sortied from Pearl Harbor in response, as the Japanese expected it would, the carriers and the battleships of the Main Body would combine to destroy it.

The sequence mattered. Yamamoto expected the Americans to react to the attack on Midway, not to be waiting for it. The plan therefore assumed that Nagumo would have a free hand against the atoll for several days and that any U.S. carriers would arrive later, from the direction of Hawaii, giving Japanese submarines and flying boats time to report them. The two operations were to begin almost together; because Nagumo’s sailing slipped by a day, the Aleutian strikes opened on 3 June, a day before the Kido Butai struck Midway.

The U.S. Navy’s 1943 narrative interpreted the Aleutian attack as possibly a diversion but, it added, “more probably” a cover for the occupation of Kiska and Attu. Parshall and Tully argue that AL was not designed as a diversion at all. It was a separate objective, run simultaneously, intended to secure the northern flank of the perimeter. Its timing, with strikes on Dutch Harbor only one day ahead of the Midway strike, would in any case have given the Americans no time to send forces north. Its real cost to the Japanese was that it took two carriers, Ryujo and Junyo, away from the Central Pacific.

Many forces, hundreds of miles apart

Operation MI committed most of the Combined Fleet, organized in separate groups with separate commanders, routes and timetables. The organization is easiest to follow from the front.

The Kido Butai (Mobile Force, formally the First Carrier Striking Force) under Nagumo, flying his flag in Akagi, consisted of the four fleet carriers Akagi, Kaga, Soryu and Hiryu; the fast battleships Haruna and Kirishima; the heavy cruisers Tone and Chikuma; and the light cruiser Nagara leading a destroyer screen. The 1943 U.S. narrative, reconstructing it from intelligence, listed the same capital ships and twelve destroyers. The carriers were the core of the force that had attacked Pearl Harbor, though two of the six Pearl Harbor carriers were missing. Parshall and Tully put the four carriers’ aircraft at 248, a total that by most accounts includes fighters being ferried for the planned Midway garrison: Akagi 60, Kaga 74, Soryu 57 and Hiryu 57.

The Main Body under Yamamoto himself followed several hundred miles behind Nagumo. It included the new battleship Yamato, the largest warship afloat, the battleships Nagato and Mutsu, the light carrier Hosho with a handful of Type 96 torpedo bombers for scouting and antisubmarine patrol, and a destroyer screen. Traveling with it at first was Vice Admiral Shiro Takasu’s Guard Force of four older battleships, Fuso, Yamashiro, Ise and Hyuga, which was to break away and take station between Midway and the Aleutians.

The Invasion Force under Vice Admiral Nobutake Kondo in Atago approached from the southwest. Kondo’s main body included the battleships Kongo and Hiei, four heavy cruisers and the light carrier Zuiho. A close support group under Vice Admiral Takeo Kurita, the heavy cruisers Kumano, Suzuya, Mikuma and Mogami, operated ahead of the transports. The transport group itself, carrying the landing troops, sailed from Saipan under Rear Admiral Raizo Tanaka in the light cruiser Jintsu, accompanied by a seaplane tender group and minesweepers.

In the north, Vice Admiral Boshiro Hosogaya’s Northern Area Force in the heavy cruiser Nachi controlled the Aleutian operation. Its striking element was Rear Admiral Kakuji Kakuta’s Second Carrier Striking Force with the light carrier Ryujo and the converted carrier Junyo, with two heavy cruisers. Separate invasion groups were to land on Attu and Kiska. Finally, Japanese submarines of the Advance Expeditionary Force were to form scouting lines between Hawaii and Midway, and a flying-boat reconnaissance of Pearl Harbor, Operation K, was to confirm that the U.S. carriers were in port.

Seen on a chart, the arrangement had a logic of its own. Each group could arrive at its assigned place on its assigned day, and the battleships, in Japanese doctrine still the arbiters of a fleet action, were held back to finish off an American fleet already weakened by air attack. Its weakness was that the force with the most capacity to absorb an American counterstroke, the battleships and the two light carriers with Kondo and Yamamoto, was too far away to take part in a carrier battle near Midway. In the event, the two light carriers, five battleships, four heavy cruisers and two light cruisers with Yamamoto and Kondo saw no action in the carrier battle. The Kido Butai had two battleships, three cruisers and a destroyer screen for its own protection.

The forces sailed on staggered dates in late May. Kakuta’s carriers had already sailed from northern Japan for the Aleutians. Nagumo’s four carriers sortied from the Hashirajima anchorage in the Inland Sea on 27 May, the anniversary of the victory at Tsushima in 1905, which the Navy observed as Navy Day. The transports left Saipan at about the same time, and Yamamoto’s Main Body and Kondo’s force followed from the Inland Sea on 29 May. These are the dates given in most modern accounts; some older works vary by a day because of the difference between Tokyo time and local time east of the date line.

The carriers that stayed home: Coral Sea’s arithmetic

The Kido Butai went to Midway with four carriers instead of six because of the Battle of the Coral Sea, fought 4–8 May 1942. Covering Operation MO, the Japanese lost the light carrier Shoho, sunk on 7 May. On 8 May the fleet carrier Shokaku took bomb hits that put her out of action for repairs, and her sister ship Zuikaku, though undamaged, lost a large part of her air group. On the American side, the carrier Lexington was lost and Yorktown damaged. The 1943 Combat Narrative’s foreword summarized the effect from the American point of view: the Coral Sea battle sank one Japanese carrier, damaged a second and mauled the air group of a third, eliminating three carriers the Japanese had planned to use at Midway.

Shokaku’s absence was unavoidable; she was in dry dock. Zuikaku’s is the subject of one of the sharpest criticisms in the modern literature. Her hull was intact, and the problem was a shortage of trained aircrew and aircraft. According to H. P. Willmott’s account, she was at Kure awaiting replacements, and instructors were pulled from the Yokosuka Air Corps to rebuild her group. Parshall and Tully argue that the Japanese could have combined the surviving aircrews of the two sister ships into a single air group for Zuikaku and sent a fifth carrier to Midway, but that the Navy’s practice of keeping carrier air groups bound to their own ships worked against improvisation. The Americans, as will be seen, did the opposite with Yorktown, assembling an air group from several squadrons in a matter of days.

The Japanese also drew the wrong conclusions about the American side of the ledger. Their aviators reported sinking two U.S. carriers at the Coral Sea. They believed Yorktown either sunk or too badly damaged to fight in June, and the Midway plan was built on intelligence suggesting that only Enterprise and Hornet were available to the Pacific Fleet. In mid-May those two carriers, returning from the Doolittle raid and hurried south too late for the Coral Sea, were sighted by Japanese patrol aircraft in the South Pacific, which reinforced the belief that the Americans were looking the other way. The plan’s assumptions about the opposition rested on information that was weeks old by the time the fleet sailed.

Rehearsal on the Yamato: the war games

Before the fleet sailed, the Combined Fleet staff tested the plan in tabletop war games aboard Yamato at Hashirajima in the first days of May 1942. The best-known account of the games comes from Fuchida and Okumiya’s postwar book. In their telling, the game controllers rolled dice for a U.S. land-based air attack on the carriers off Midway and scored nine hits, sinking Kaga and Akagi. Rear Admiral Matome Ugaki, Yamamoto’s chief of staff, who presided, reduced the hits to three, so that Kaga was sunk and Akagi only damaged; Kaga then reappeared in the next phase of the game, for the operations against Fiji and New Caledonia.

The story is often told as proof that the Japanese ignored warning signs out of overconfidence. It needs care. Fuchida’s postwar writing is the main source for it, and Parshall and Tully have shown that Fuchida was unreliable on several important points about Midway, notably his claim that the carriers were only minutes from launching a counterstrike when the American dive bombers struck. That does not mean the war-game episode is invented, and later historians including Gordon Prange accepted it; it does mean the dialogue and details attached to it in popular retellings are later recollection, not contemporary record.

The larger point the games are used to illustrate holds independently of the dice. The plan did not seriously examine what would happen if the American carriers were already at sea when Nagumo arrived. The Kido Butai was told to strike Midway and to be ready for the U.S. fleet, two missions that required different preparations on the hangar decks: bombs for land targets, torpedoes and armor-piercing bombs for ships. Japan’s scouting arrangements for the carriers themselves were thin. Those gaps were not hidden; they were treated as acceptable because the planners did not expect to need the answers until days after the first strike on Midway. In the event, the problem fell on Nagumo’s flight decks on the morning of 4 June, as Chapter 5 describes.

Eyes that never opened: the submarine cordon and Operation K

The Japanese plan included two measures to detect an American sortie from Pearl Harbor. Both failed before the battle began, and their failure is central to why the U.S. carriers reached their ambush position unseen.

The first was a cordon of submarines. Boats of the Sixth Fleet were to take station on scouting lines between Hawaii and Midway, where any U.S. force heading for Midway from Pearl Harbor would have to pass. The Japanese did not expect the Americans to sail before the attack on Midway, and the submarines were late. In the words of the Naval History and Heritage Command’s account, the Japanese had planned to station submarines to watch for an American sortie but did not expect it so soon, and the “Japanese subs were not yet on station.” Modern accounts attribute part of the delay to the haste with which the operation’s date had been set. By the time the boats reached their lines in early June, Task Forces 16 and 17 had already passed through the area.

The second measure was a repeat of Operation K, the long-range flying-boat raid that had reached Oahu on the night of 4 March 1942. In that operation, two Kawanishi H8K flying boats, led by Lieutenant Hisao Hashizume, had flown from the Marshall Islands, refueled from submarines at French Frigate Shoals, a reef and sandbar group in the Northwestern Hawaiian Islands, and dropped bombs that fell harmlessly near Honolulu. For Midway the Japanese planned to repeat the refueling at French Frigate Shoals and fly a reconnaissance over Pearl Harbor around 30 May to confirm that the U.S. carriers were still in port.

Nimitz had already closed that door. After the March raid the Americans recognized how it had been staged and stationed ships at French Frigate Shoals; the converted destroyers Ballard and Thornton, serving as seaplane tenders, are the ships associated with the anchorage in this period. When the submarine I-123 arrived to prepare the refueling point at the end of May, she found the area mined and U.S. warships at anchor. The Japanese considered an alternative site and then cancelled the flight. As the National WWII Museum’s account notes, the location of the U.S. carriers then remained unknown to the Japanese until a scout plane from the cruiser Tone found them near Midway on the morning of 4 June.

These failures had a common cause: the plan’s timetable assumed the Americans would move second. Watanabe’s explanation to his U.S. interrogators in October 1945 focused on the same point, though he blamed different people. He said the air force had failed to maintain an adequate search for the American carriers and that the submarines had been stationed too far east to find the American fleet. Both statements describe the same failure from different angles: the Japanese had no reliable picture of where the U.S. carriers were on 3 June.

Nimitz’s problem

Chester W. Nimitz had taken command of the Pacific Fleet on 31 December 1941, inheriting a fleet whose battleships were sunk or under repair and whose striking power lay in a handful of carriers. By mid-May 1942 he had two carriers ready, Enterprise and Hornet, both in the South Pacific; one, Yorktown, damaged and on her way back from the Coral Sea; and one, Saratoga, completing repairs on the West Coast after a torpedo hit in January. Against him, if the codebreakers were right, the Japanese were about to send most of their fleet.

The intelligence picture developed through May. NHHC’s photo-history summarizes it: by mid-May Pacific Fleet codebreakers reported that the Japanese planned to attack “somewhere in the Hawaiian area, as well as in the Aleutians,” and by 26 May they were certain the target was Midway. The work of Commander Joseph J. Rochefort’s Station HYPO at Pearl Harbor, the dispute with analysts in Washington over the target and the date, and the water-distiller ruse that confirmed “AF” as Midway are covered in Chapter 1 and on the Station HYPO unit page. What matters here is the operational choice it forced. The intelligence was good, but not certain, and acting on it meant risking the fleet’s remaining carriers on a forecast.

Nimitz had already acted on the strategic picture before the intelligence was complete. He had flown to Midway on 2 May to inspect its defenses and asked the local commanders, Commander Cyril T. Simard and Lieutenant Colonel Harold D. Shannon of the 6th Defense Battalion, what they needed to hold against a major attack. In the following weeks he sent the atoll everything Pearl Harbor could spare: more Marine aircraft, Army B-17s and B-26s, a detachment of the Navy’s new TBF Avenger torpedo bombers, PT boats, guns and Marines. By 3 June, according to the ONI narrative, Midway held 14 PBY-5 and 16 PBY-5A patrol planes, 4 B-26s, 17 B-17s and 6 TBFs, in addition to the Marine fighters and dive bombers of Marine Aircraft Group 22. The atoll would serve as a fixed aircraft carrier that could not be sunk.

The carriers were the harder decision. Halsey’s Task Force 16 had been sent south after the Doolittle raid to support the defense of the Coral Sea area and had arrived too late for the battle. Nimitz recalled it to Pearl Harbor. Admiral Ernest J. King in Washington, Commander in Chief, U.S. Fleet, had his own concerns about Japanese moves in the South Pacific and in the Aleutians, and the two admirals had to reconcile their views by message before Nimitz’s dispositions were settled. In the end King accepted Nimitz’s assessment. The ONI narrative records the guidance that framed it: King directed “strong attrition tactics” and specified that carriers and cruisers were not to be “unduly risked.”

For the northern threat Nimitz formed Task Force 8 under Rear Admiral Robert A. Theobald, a cruiser-and-destroyer force for the Aleutians, and he did not send carriers north. The old battleships of the Pacific Fleet, which had been reformed on the West Coast as Task Force 1, were not brought forward; they were too slow to operate with the carriers and would have needed air cover the fleet could not spare. Nimitz’s choice was to concentrate all three available carriers at Midway and fight there.

Halsey’s hospital bed and Spruance’s command

Enterprise and Hornet entered Pearl Harbor on 26 May. Halsey came ashore ill. Weeks of strain at sea had left him with a severe skin disease, generally described as dermatitis and often called shingles in later accounts, and he was hospitalized. He could not command Task Force 16 for the coming battle. NHHC’s photo-history calls him simply “the ailing Halsey.”

Halsey recommended as his replacement Rear Admiral Raymond A. Spruance, who commanded the cruisers of his screen. The choice was unusual. Spruance was not an aviator and had never commanded carriers. He took over Halsey’s staff intact, including the chief of staff, Captain Miles R. Browning, an aviator, and went to sea with a force whose air operations were run by men he had not worked with as a commander. Nimitz approved the recommendation, and the choice would shape the battle; Spruance’s decisions on the morning of 4 June and the night of 4–5 June are covered in Chapter 4 and Chapter 7.

Command of the combined force went to Rear Admiral Frank Jack Fletcher, the senior of the two task force commanders, who had commanded Yorktown’s Task Force 17 at the Coral Sea. Fletcher had lost Lexington there, and his handling of the carriers in the South Pacific had drawn criticism in Washington. Nimitz met with him after Yorktown’s return and kept him in command; John Lundstrom’s biography of Fletcher, Black Shoe Carrier Admiral (2006), treats this as a considered vote of confidence after Nimitz reviewed his conduct of the Coral Sea battle. Fletcher would be officer in tactical command at Midway, flying his flag in Yorktown, with Spruance operating Task Force 16 nearby under his general direction.

Three days in Dry Dock No. 1

Yorktown reached Pearl Harbor on 27 May, trailing oil. At the Coral Sea on 8 May a bomb had struck her flight deck inboard of the island, penetrated several decks and exploded, wrecking compartments and starting fires, while near misses opened seams in her hull plating and ruptured fuel tanks. The damage report written by her captain, Elliott Buckmaster, went ahead of her. Estimates before her arrival spoke of months of work, likely at the Puget Sound Navy Yard on the West Coast; Defense Media Network’s account of the repair records Rear Admiral Aubrey Fitch’s estimate of ninety days.

Nimitz could not wait months. Yorktown went into Dry Dock No. 1 at the Pearl Harbor Navy Yard, and Nimitz inspected the hull in person from the floor of the dock. The yard’s workers, about 1,400 of them according to most accounts, worked around the clock on the essential repairs only. They patched the hull with steel plate rather than repairing each opened seam, shored up and replaced damaged internal structure, and restored what could be restored to the ship’s systems. Damage that did not affect her ability to steam and operate aircraft was left. NHHC dates the urgent repairs in dry dock to 29 May, and an official U.S. Navy photograph shows her in the dock that day.

The 1943 Combat Narrative put the result plainly: it proved possible to restore Yorktown and her planes to fighting condition in three days, and she sailed on the 30th. Later accounts commonly describe the repair as a 72-hour job and note that the ship was fit for a few weeks of operations, not restored to full strength. The repaired Yorktown could steam and fly aircraft, but several of her compartments were not fully restored, a fact that would matter when she was hit again on 4 June. Her story in the battle is told in Chapter 6 and on the USS Yorktown unit page.

The air group was rebuilt as fast as the ship. Yorktown’s own fighter and torpedo squadrons had been worn down at the Coral Sea. For Midway she embarked squadrons from Saratoga, which was still on the West Coast: Bombing Squadron 3 under Lieutenant Commander Maxwell F. Leslie, Torpedo Squadron 3 under Lieutenant Commander Lance E. Massey, and a rebuilt Fighting Squadron 3 under Lieutenant Commander John S. Thach, filled out with pilots from Yorktown’s own Fighting 42. Yorktown’s surviving dive bombers flew as Scouting 5. NHHC summarizes the arrangement as Yorktown sailing with “a new air group formerly belonging to Saratoga.”

“The principle of calculated risk”

Nimitz’s operation plan for Midway, Operation Plan 29-42, assigned the carriers to operate northeast of Midway, out of range of Japanese search as long as possible, and to strike the Japanese carriers on the flank when they committed to their attack on the atoll. The intent was to reverse the expected sequence of the battle: instead of the Japanese finding the Americans after the attack on Midway, the Americans would be in position before it and would locate the Japanese first, using Midway’s long-range PBY patrols.

On 28 May, the day Task Force 16 sailed, Nimitz gave his carrier commanders a letter of instruction that addressed the tension in King’s guidance between attrition and caution. As quoted by Captain James McGrath in Proceedings (June 2018), it began:

You will be governed by the principle of calculated risk …

— Adm. Chester W. Nimitz, letter of instruction to the striking force commanders, 28 May 1942 (as quoted in U.S. Naval Institute Proceedings, June 2018)

The letter went on to define the principle as the avoidance of exposing the force to attack by superior enemy forces unless there was a good prospect of inflicting greater damage on the enemy as a result. In practice it told Fletcher and Spruance to strike hard if they could hit the Japanese carriers first, and not to fight a battle of attrition against superior surface forces they could not win. It did not tell them how to weigh those risks in the moment; it left that judgment to them. Spruance’s later decisions not to press westward at night into the path of the Japanese battleships are usually read in light of this instruction.

King, writing the foreword to the Combat Narrative in January 1943, used the same phrase when explaining why the battle had gone as it did. He credited “Admiral Nimitz’s informed willingness to take a calculated risk.” The word “informed” pointed, as far as wartime secrecy allowed, to the intelligence behind the decision, which could not be described in a document distributed throughout the Navy in 1943.

To Point Luck

Task Force 16 left Pearl Harbor on 28 May: Enterprise and Hornet, the heavy cruisers Northampton, Pensacola, Vincennes, Minneapolis and New Orleans, the light antiaircraft cruiser Atlanta, and a destroyer screen. Task Force 17 followed on 30 May with Yorktown, the heavy cruisers Astoria and Portland, and destroyers. The 1943 Combat Narrative lists nine destroyers with Spruance and five with Fletcher; later order-of-battle tables add a sixth, Gwin, to Task Force 17. Oilers went with the task forces, and both refueled at sea en route.

The two task forces met on 2 June northeast of Midway. The ONI narrative gives the rendezvous position as latitude 32°04′ N, longitude 172°45′ W, about 350 miles northeast of Midway; NHHC’s summary describes it as “some three hundred miles northeast of Midway.” The 1943 narrative gives only the coordinates; Point Luck is the name by which the position is generally known. From there, Fletcher and Spruance planned to operate separately but within supporting distance, waiting for Midway’s patrol planes to find the Japanese carriers.

Behind the carriers, nineteen U.S. submarines took positions covering the approaches to Midway, most of them in an arc west and northwest of the atoll. One of them, Nautilus, would play a part on 4 June out of all proportion to her one unsuccessful torpedo attack, as Chapter 5 explains. Saratoga, with her repairs completed, sailed from San Diego but did not reach Pearl Harbor until 6 June, too late for the battle.

1. 18 Apr 1942Doolittle’s sixteen B-25s launch from Hornet and bomb Tokyo and other cities; Japanese opposition to the Midway plan collapses.
2. 1–4 MayCombined Fleet war games aboard Yamato at Hashirajima test the MI and later phases of the plan.
3. 4–8 MayBattle of the Coral Sea: Shoho sunk, Shokaku damaged, Zuikaku’s air group depleted; Lexington lost and Yorktown damaged.
4. 5 MayImperial General Headquarters Navy Order No. 18 directs the occupation of Midway and the western Aleutians (per Fuchida).
5. 26 MayEnterprise and Hornet return to Pearl Harbor; Halsey is hospitalized and Spruance chosen for TF16.
6. 27 MayNagumo’s Kido Butai sorties from Hashirajima. Yorktown reaches Pearl Harbor.
7. 28 MayTF16 sails from Pearl Harbor. Nimitz issues his letter of instruction.
8. 29 MayYorktown under emergency repair in Dry Dock No. 1. Yamamoto’s Main Body and Kondo’s force leave the Inland Sea.
9. c. 30 MayPlanned date for the Operation K flight over Pearl Harbor; cancelled after I-123 finds U.S. ships at French Frigate Shoals.
10. 30 MayTF17 sails with Yorktown and her new air group.
11. 2 JunTF16 and TF17 rendezvous northeast of Midway at the position known as Point Luck.
12. 3 JunJapanese carrier aircraft strike Dutch Harbor; a Midway PBY sights the Japanese Invasion Force west of the atoll.

On the Japanese side the approach went largely to schedule. Nagumo’s carriers ran east under weather fronts that hid them from American patrols but also complicated navigation and kept the ships out of visual contact with one another for periods. The transport group, coming from the southwest on a more direct line, was the first Japanese element the Americans found. On 3 June a PBY from Midway sighted Japanese ships west of the atoll, and Midway’s B-17s attacked the transports that afternoon without result. The battle had begun, and the Kido Butai, still unseen, was closing from the northwest. That story is told in Chapter 3.

Order of battle: how the scales actually stood

Counted ship for ship, Operation MI was one of the largest naval operations attempted to that point in the war. Japan committed eight carriers of all sizes to MI and AL together, eleven battleships, about two dozen cruisers and dozens of destroyers. The United States had three carriers, no battleships in the battle area, eight cruisers and fourteen or fifteen destroyers with the carrier task forces. Totals of destroyers and auxiliaries vary between sources depending on whether oiler escorts, minesweepers and patrol craft are counted; the table below uses the 1943 ONI narrative for the U.S. carrier forces and the order-of-battle tables compiled from Prange and the 1948 Naval War College analysis for the Japanese.

The numbers that mattered most were the last line. In the battle that the plan actually produced, the four carriers of the Kido Butai fought the three American carriers and Midway’s land-based aircraft, and the surface ships on both sides played little direct part in the fighting of 4 June. The U.S. carriers embarked about 230 aircraft. The 1943 ONI narrative gives each of Enterprise and Hornet 35 scout and dive bombers, 14 torpedo bombers and 27 fighters, and Yorktown 36, 12 and 25, for a total of 225; later counts, including Lundstrom’s, are usually around 233. Nagumo’s carriers had 248 by Parshall and Tully’s count, and by most accounts some of those were fighters ferried for the future Midway garrison rather than part of the operational air groups. Add Midway’s land-based aircraft, and the Americans had more aircraft in the battle area than the Japanese did.

What the plan assumed, and what it got

Seen with hindsight, Plan MI rested on a chain of assumptions, each reasonable on its own terms. The Americans would not know the Japanese were coming. They would have at most two carriers available. They would react to the attack on Midway rather than anticipate it, and when they did, Japanese submarines and flying boats would report their movement. The Kido Butai would therefore have time to neutralize Midway before facing any American carrier force, and the battleships would arrive to complete the destruction of whatever the carriers had damaged.

Every link failed. The Americans read enough of the Japanese radio traffic to know the target, the approximate date and the general composition of the force. They had three carriers, not two, because of the repair of Yorktown. They sailed before the Japanese submarines were in place, and the reconnaissance flight that might have shown the empty berths at Pearl Harbor was cancelled because U.S. ships were sitting at its refueling point. When the battle began, Nagumo was carrying out the first half of his mission, the strike on Midway, against an enemy who was already in position to carry out the second half against him.

None of this made the outcome certain. The American position depended on finding the Japanese carriers first and then hitting them with air groups of uneven experience, using torpedo bombers that were obsolete and torpedoes that often failed. The Japanese carriers had the best-trained aircrews in the world and fighters superior to most of what the Americans could put up. The morning of 4 June would show both the advantage the American plan had created and how close it came to being wasted. The next chapters follow it hour by hour, beginning with the atoll and its defenders in Chapter 3.

The judgment of historians on the plan has moved over time. The early American narratives, without Japanese sources, emphasized U.S. courage and good fortune against a vastly superior enemy. Postwar Japanese accounts, Fuchida’s above all, explained the defeat as the result of bad luck in the last minutes before the dive bombers arrived. Parshall and Tully’s study moved the explanation back into the planning: the dispersal of the fleet, the failure to bring Zuikaku, the dependence on a timetable the Americans had no reason to follow, and a doctrine that held the battleships back for a decisive surface engagement that never came. Symonds and Lundstrom gave equal weight to the American side of the ledger: the intelligence, Nimitz’s decision to act on it, and the dispositions of Fletcher and Spruance. The Japanese did not lose Midway in the planning rooms of April and May 1942, but those rooms produced the conditions in which they could lose it in a single morning.