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Battle of Midway - Prelude to battle

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Yamamoto's plan
Prelude to battle
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Prelude to battle

American reinforcements

USS Yorktown at Pearl Harbor days before the battle.
In order to do battle with an enemy force anticipated to muster four or five 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 unavailable, still under repair on the West Coast, while Yorktown had been severely damaged at the Battle of the Coral Sea. Despite estimates that Yorktown would require several months of repairs at Puget Sound, her elevators had remained intact, and her flight deck largely so. Consequently, Pearl Harbor Naval Shipyard worked around the clock and in 72 hours, she was restored to a battle-ready state, judged good enough for two or three weeks of operations, as Nimitz required. Her flight deck was patched, whole sections of internal frames cut out and replaced, and several new squadrons (drawn from Saratoga) were taken aboard; they did not, however, get time to train. Nimitz disregarded 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 way.

On Midway Island, the USAAF stationed four squadrons of B-17 Flying Fortresses, along with several B-26 Marauders. The Marine Corps had nineteen SBD Dauntless dive bombers, seven F4F-3 Wildcats, seventeen Vought SBU-3 Vindicators, twenty-one F2A-3 Brewster Buffalos, and six Grumman TBF-1 Avenger torpedo bombers, the latter a detachment of VT-8 from Hornet.

Japanese shortcomings

Akagi in April 1942, the flagship of the Japanese carrier striking force which attacked Pearl Harbor, as well as Darwin, Rabaul, and Colombo, prior to the battle.
Meanwhile, as a result of her participation in the Battle of the Coral Sea, the Japanese carrier Zuikaku was in port in Kure, awaiting a replacement air group. That there were none immediately available was a failure of the IJN crew training program, which already showed signs of being unable to replace losses. Instructors from the Yokosuka Air Corps were employed in an effort to make up the shortfall. 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, Admiral Nagumo would only have four fleet carriers: Kaga and Akagi forming Division 1; Hiryū and Sōryū as Division 2. At least part of this was a product of fatigue; Japanese carriers had been constantly on operations since 7 December, 1941, including raids on Darwin and Colombo.

The main Japanese strike aircraft to be used were the Aichi D3A1 dive bomber and the Nakajima B5N2, which was capable of being used either as a torpedo bomber or as a level attack bomber. The main carrier fighter was the fast and highly maneuverable Mitsubishi A6M2 Zero. However, the carriers of the Kido Butai were suffering from a shortage of frontline aircraft. For various reasons, production of the D3A had been drastically reduced, while that of the B5N had been stopped completely. As a consequence, there were none available to replace losses. This also meant that many of the aircraft being used during the June 1942 operations had been operational since late November 1941; although well maintained, they were almost worn out and had become increasingly unreliable. These factors meant that all carriers had less than their normal aircraft complement and few spare aircraft.

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 reach their assembly point northeast of Midway (known as "Point Luck") without being detected. A second attempt at reconnaissance, using four-engine Kawanishi H8K flying boats to scout Pearl Harbor prior to the battle (and thereby detect the absence or presence of the American carriers), part of "Operation K", was also thwarted when Japanese submarines assigned to refuel the search aircraft discovered that 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 March). 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 message traffic. This information was in Yamamoto's hands prior to the battle. However, Japanese plans were not changed; Yamamoto, at sea on Yamato, did not dare inform Nagumo for fear of exposing his position and assumed incorrectly that Nagumo had received the same signal from Tokyo.

Allied code-breaking

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, to determine the date of the attack as either 4 or 5 June, and to provide Nimitz with a complete IJN order of battle. Japan's efforts to introduce a new codebook had been delayed, giving HYPO several crucial days; while it was blacked out shortly before the attack began, the important breaks had already been made.

As a result, the Americans entered the battle with a very good picture of where, when, and in what strength the Japanese would appear. Nimitz was aware, for example, that the vast numerical superiority of the Japanese fleet had been divided into no less than four task forces, and the escort for the main Carrier Striking Force was limited to just a few fast ships. For this reason, they knew that the anti-aircraft guns protecting the carriers would be limited. Knowing the strength he faced, Nimitz calculated his three carrier decks, plus Midway Island, to Yamamoto's four, gave the U.S. rough parity (although American carrier air groups were larger than Japanese ones). The Japanese, by contrast, remained almost totally unaware of their opponent's true strength and dispositions even after the battle began.

Last Updated ( Thursday, 16 April 2009 20:56 )