|Battle of Midway|
|Prelude to battle|
|Attacks on the Japanese fleet|
|Discovery of sunken vessels|
Prelude to battle
USS Yorktown at Pearl Harbor days before the battle.
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.
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.
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.
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.