Eastern Operation: Japan's Plan to Invade Hawaii 1941

Japan’s Eastern Operation was the planned, but never executed (with regret), planned invasion of Oahu, Hawaii, during the attack on Pearl Harbor in 1941. Talked about and debated for many years prior to 1941 in Japan, this invasion using up to three infantry divisions, was to retake what many Japanese thought belonged to them-Hawaii. Militarily, most Japanese commanders felt America would retreat from their colony. Whether this was true or not, the achilles heel for the Japanese was time and supply.

The plan had to be successful within a week, otherwise, the Japanese troops would become isolated and deprived of supplies. Admiral Yamamoto was quite hesitant about the plan, while other naval commanders fully supported it. The Army, ironically, was more hesitant than even Yamamoto, mainly because of the logistical nightmare requiring 20-25 transports a week traveling 4000 miles from Japan to sustain the garrison. The plan to invade Oahu or Hawaii never occurred, but was close to becoming reality. It was again suggested in 1942 after Midway was to be occupied. Ironically, after Yamamoto heard of the complete surprise at Pearl Harbor, he expressed regret about not invading Oahu. He said it was a “missed opportunity”, one he should’ve taken.

Had it happened, there was a chance that the US might abandon the Oahu outpost, which in 1941, was considered expendable by many in the US Senate and Congress. After Japan attacked PH, many of them cried out to abandon the base and fall back to the big island of Hawaii or to the West Coast. Judging from the chaos the real PH attack upon the US, had the Japanese also landed troops, the shock impact would have been dramatic and even more chaos would have ensued.