The Japanese operation, like the earlier attack on Pearl Harbor, aimed to eliminate the United States as a strategic power in the Pacific, thereby giving Japan a free hand in establishing its Greater East Asia Co-Prosperity Sphere. It was hoped another demoralizing defeat would force the U.S. to negotiate an end to the Pacific War on conditions favorable to Japan.
The Japanese plan was to lure the United States’ few remaining carriers into a trap.The Japanese also intended to occupy Midway Atoll as part of an overall plan to extend their defensive perimeter in response to the Doolittle Raid. This operation was considered preparatory for further attacks against Fiji and Samoa.
The plan was handicapped by faulty Japanese assumptions of American reaction and poor initial dispositions.Most significantly, American code breakers were able to determine the date and location of the attack, enabling the forewarned U.S. Navy to set up an ambush of its own. Four Japanese aircraft carriers and a heavy cruiser were sunk in exchange for one American aircraft carrier and a destroyer. The heavy losses in carriers and aircrews permanently weakened the Imperial Japanese Navy.Japanese shipbuilding and pilot training programs in providing replacements were unable to keep pace even with her own losses, while the U.S. steadily increased output in both areas.
Japan had been highly successful in swiftly securing its initial war goals, including the conquest of the Philippines, Malaya, Singapore, and the Dutch East Indies (now Indonesia) with its vital resources. As such, preliminary planning for a second phase of operations commenced as early as January 1942. 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 April 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 thinly-veiled threat to resign unless he got his way carried his agenda forward.
Yamamoto’s primary strategic concern was the elimination of America’s remaining carrier forces, which he perceived as the principal obstacle to the overall Pacific campaign.This concern was acutely heightened by the Doolittle Raid on Tokyo (18 April 1942) by USAAF B-25s launched from USS Hornet. The raid, while militarily insignificant, was a severe psychological shock to the Japanese and showed the existence of agap in the defenses around the Japanese home islands Sinking America’s aircraft carriers and seizing Midway, the only strategic islands besides Hawaii in the eastern 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. 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, but the Japanese felt the Americans would consider Midway a vital outpost of Pearl Harbor and would therefore strongly defend it.The U.S. did consider Midway vital; after the battle, establishment of a U.S. submarine base on Midway allowed submarines operating from Pearl Harbor to refuel and reprovision, extending their radius of operations by 1,200 miles (1,900 km). An airstrip on Midway served as a forward staging point for bomber attacks on Wake Island.