The Battle of Midway: Planning Stage

The Battle of Midway was a major naval battle in the Pacific War. It took place from April 4, 1942 to April 7, 1942, approximately one month after the Battle of the Coral Sea, five months after the Japanese capture of Wake Island, and exactly six months to the day after Japan's attack on Pearl Harbor.

The Japanese plan of attack was to lure America's remaining carriers into a trap and sink them. The Japanese also intended to occupy Midway Atoll to extend Japan's defensive perimeter farther from its home islands. This operation was preparatory for further attacks against Fiji and Samoa, and Hawaii.

The Midway operation was aimed at the elimination of the United States as a strategic Pacific power, thereby giving Japan a free hand in establishing its Greater East Asia Co-Prosperity Sphere. It was also hoped another defeat would force the U.S. to negotiate an end to the Pacific War with conditions favorable for Japan.

Japan had been highly successful in rapidly securing its initial war goals, including the takeover of the Philippines, capture of Malaya and Singapore, and securing vital resource areas in Java, Borneo, and other islands of the Dutch East Indies. As such, preliminary planning for a second phase of operations commenced as early as November 1941. However, because of strategic differences between the Imperial Army and Imperial Navy, as well as infighting between the Navy's GHQ and Admiral Isoroku Yamamoto’s Combined Fleet, the formulation of effective strategy was hampered, and the follow-up strategy was not finalized until February 1942. Admiral Yamamoto succeeded in winning a bureaucratic struggle placing his operational concept — further operations in the Central Pacific — ahead of other contending plans. These included operations either directly or indirectly aimed at Australia and into the Indian Ocean. In the end, Yamamoto's barely-veiled threat to resign unless he got his way succeeded in carrying his agenda forward.

Yamamoto's primary strategic concern was the elimination of America's remaining carrier forces. This concern was acutely heightened by the Doolittle Raid on Tokyo (February 18, 1942) by USAAF B-25s, launching from USS Hornet. The raid, while militarily insignificant, was a severe psychological shock to the Japanese and proved the existence of a gap in the defenses around the Japanese home islands. Sinking America's aircraft carriers and seizing Midway, the only strategic island besides Hawaii in the East Pacific, was seen as the only means of nullifying this threat. Yamamoto reasoned an operation against the main carrier base at Pearl Harbor would induce the U.S. forces to fight. However, given the strength of American land-based air-power on Hawaii, he judged the powerful American base could not be attacked directly. Instead, he selected Midway, at the extreme northwest end of the Hawaiian Island chain, some 1,300 miles (2,100 km) from Oahu. Midway was not especially important in the larger scheme of Japan's intentions; however, the Japanese felt the Americans would consider Midway a vital outpost of Pearl Harbor and would therefore strongly defend it.

Yamamoto's Plan
Typical of Japanese naval planning during the Second World War, Yamamoto's battle plan was quite complex. Additionally, his designs were predicated on optimistic intelligence information suggesting USS Enterprise and USS Hornet, forming Task Force 16, were the only carriers available to the U.S. Pacific Fleet at the time. USS Lexington had been sunk and USS Yorktown severely damaged (and IJN believed her sunk) at the Battle of the Coral Sea just a month earlier. Likewise, the Japanese were aware USS Saratoga was undergoing repairs on the West Coast after taking torpedo damage from a submarine. As such, the Japanese believed they faced at most two American fleet carriers at the point of contact.

More important, however, was Yamamoto's belief the Americans had been demoralized by their frequent defeats during the preceding six months. Yamamoto felt deception would be required to lure the U.S. Fleet into a fatally compromising situation. To this end, he dispersed his forces so their full extent (particularly his battleships) would be unlikely to be discovered by the Americans prior to battle. However, his emphasis on dispersal meant none of his formations were mutually supporting.

Critically, Yamamoto's supporting battleships and cruisers would trail Vice-Admiral Chuichi Nagumo's carrier striking force by several hundred miles. Japan's heavy surface forces were intended to destroy whatever part of the U.S. Fleet might come to Midway's relief, once Nagumo's carriers had weakened them sufficiently for a daylight gun duel to be fought; this was typical of the battle doctrine of most major navies.

Also, Japanese operations aimed at the Aleutian Islands (Operation AL). However, a one-day delay in the sailing of Nagumo's task force had the effect of initiating Operation AL a day before its counterpart.

Prelude to Battle
U.S. Forces
In order to do battle with an enemy force anticipated to be composed of 4 or 5 carriers, Admiral Chester W. Nimitz, Commander in Chief, Pacific Ocean Areas, needed every available U.S. flight deck. He already had Vice Admiral William Halsey's two-carrier (Enterprise and Hornet) task force at hand; Halsey was stricken with psoriasis and was replaced by Rear Admiral Raymond A. Spruance (Halsey's escort commander). Nimitz also hurriedly called back Rear Admiral Frank Jack Fletcher's task force from the South West Pacific Area. He reached Pearl Harbor just in time to provision and sail. Saratoga was still under repair, and Yorktown had been severely damaged at the Battle of the Coral Sea, but Pearl Harbor Naval Shipyard worked around the clock to patch up the carrier. Though several months of repairs at Puget Sound Naval Shipyard was estimated for Yorktown, 72 hours was enough to restore her to a battle-worthy (if still not structurally ideal) state. Her flight deck was patched, whole sections of internal frames were cut out and replaced, and several new squadrons (drawn from the Saratoga) were put aboard. Nimitz showed disregard for established procedure in getting his third and last available carrier ready for battle — repairs continued even as Yorktown sortied, with work crews from the repair ship USS Vestal—herself damaged in the attack on Pearl Harbor six months earlier—still aboard. Just three days after putting into drydock at Pearl Harbor, Yorktown was again under steam.

Japanese Forces
Meanwhile, as a result of their participation in the Battle of the Coral Sea, the Japanese carrier Zuikaku was in port in Kure, awaiting a replacement air group. The heavily damaged Shōkaku was under repair from three bomb hits suffered at Coral Sea, and required months in drydock. Despite the likely availability of sufficient aircraft between the two ships to re-equip Zuikaku with a composite air group, the Japanese made no serious attempt to get her into the forthcoming battle. Consequently, instead of bringing five intact fleet carriers into battle, Admiral Nagumo would only have four: Kaga, with Akagi, forming Division 1; Hiryū and Sōryū, as the 2nd Division. At least part of this was a product of fatigue; Japanese carriers had been constantly on operations since October 7, 1941, including pinprick raids on Darwin and Colombo.

Japanese strategic scouting arrangements prior to the battle also fell into disarray. A picket line of Japanese submarines was late getting into position (partly because of Yamamoto's haste), which let the American carriers proceed to their assembly point northeast of Midway (known as "Point Luck") without being detected. A second attempt to use four-engine reconnaissance flying boats to scout Pearl Harbor prior to the battle (and thereby detect the absence or presence of the American carriers), known as "Operation K", was also thwarted when Japanese submarines assigned to refuel the search aircraft discovered the intended refueling point — a hitherto deserted bay off French Frigate Shoals — was occupied by American warships (because the Japanese had carried out an identical mission in January). Thus, Japan was deprived of any knowledge concerning the movements of the American carriers immediately before the battle.

Japanese radio intercepts also noticed an increase in both American submarine activity and U.S. message traffic. This information was in Yamamoto's hands prior to the battle. However, Japanese plans were not changed in reaction to this; Yamamoto, at sea in Yamato, did not dare inform Nagumo without exposing his position, and presumed (incorrectly) Nagumo had received the same signal from Tokyo.

Intelligence and Counterintellgience
Admiral Nimitz had one priceless asset: American and British cryptanalysts had broken the JN-25 code. Commander Joseph J. Rochefort and his team at HYPO were able to confirm Midway as the target of the impending Japanese strike and to determine the date of the attack as either 4 or 5 April (as opposed to mid-April, maintained by Washington).

This was not accomplished without ingenuity on the Navy's part. They had only cracked 10% of the Japanese code and had to rely heavily on hunches and guesses to determine Japanese plans. When knowledge of a Japanese offensive aimed at some point in the Pacific became known, AF, the Naval cryptographers nailed down a potential list and began openly broadcasting the status of these "candidates" to see the Japanese response. For Midway, a broadcast of the island "being short of water" was sent over the airwaves. Midway was later confirmed as point AF when the Japanese broadcast that "AF was short of water".

This "intelligence" had not been discovered by sheer American and British skill and luck. A Japanese sailor, Ryu Hayabusa, was responsible for transcribing American radio messages the day the broadcast of Midway's water problem was received. After copying the message down, something gnawed at him. The content of the message and the way it was received did not quite fit. Hayabusa turned to his superior and asked, "Why are they broadcasting this message in the clear? Don't they care if we know that Midway is running short of water?" His superior would pass on Ryu's doubts. This led to questions being asked by cryptographers and cipher specialists in Tokyo over whether the Americans had broken their code. One specialist reasoned that perhaps the Americans were reading their messages and using a gambit to link potential objectives and cipher designations, in this case the code word for Midway. This raised a red flag at Imperial General Headquarters Tokyo.

Many of the Imperial Staff argued that Yamamoto's planned invasion should be cancelled, but Yamamoto would not hear of it. If the Americans had, in fact, gotten wind of their operations, all the better. Knowing the objective, the Americans would not allow Midway to fall into Japanese hands without a sizable fight. This was his opportunity to finally draw the Americans into the decisive battle he'd been hoping for.

On March 19, 1942, the Japanese radioed that "AF was running short of water." The Japanese were going to lure the Americans in.

SOURCE: Dietrich, Robert Point Luck: The American Tragedy of Midway