In March 1942, Pilot Lieutenant Hisao Hashizume boarded his craft on a remote atoll in the Marshall Islands. His craft was a Kawanishi H8K, a flying boat designed to take off and land on water. The H8K was also designed with another important feature: it could fly very long distances without refueling. It had to because Hashizume was heading to Pearl Harbor, Hawaii, a distance of over 2,000 miles. The Japanese had shocked the world with their attack on Pearl Harbor the previous December. And now, they were going to do it again.
Hashizume’s mission was codenamed Operation K, and it was designed to help correct an important failure of the original Pearl Harbor operation. The idea behind the surprise attack at Pearl Harbor was to cripple the US Pacific Fleet while it was docked. It was estimated that this would give the Japanese a good six months during which they could operate in the Pacific without any interference. And they had already put this headstart to use since the attack, capturing Singapore, the Philippines, and the Dutch East Indies. In terms of overall strategy, the plan was to construct a chain of defenses far away from the home islands they could use to block the Americans.
But by March 1942, there were already signs that the attack on Pearl Harbor hadn’t achieved the results the Japanese wanted. The attack had sunk or damaged 8 battleships, and 9 smaller screening vessels, a significant portion of the US Navy’s strength in the Pacific. But it wasn’t enough. Many of the ships sunk had already been raised from the bottom of the bay, and extensive repair operations were underway at a pace the Japanese hadn’t expected. Combined with the new ships rapidly being built, the window for Japan to operate before a re-built US Navy crushed their own was shrinking.
Operation K was supposed to achieve two objectives to help the Japanese slow down the US repair efforts. First, it would provide valuable information about how many ships were at Pearl Harbor and what their state of repair was. Second, the planes would drop bombs on the base, disrupting further repair efforts. Naval planners hoped that if Operation K succeeded, it would open the door to further attacks. With enough air attacks, the Japanese could secure a little extra time to strengthen their defenses in the Pacific before the US fleet was ready for combat.
But from the beginning, the problems with launching a second raid on Pearl Harbor were obvious. All of the challenges the Japanese faced with the first attack were still there, but now the US couldn’t be taken by surprise. There was also a shortage of planes to carry out the attack. Of the five H8K’s that the Navy requested, only two were available for the raid. There were no fighters with the range to escort the bombers either, which meant they had little defense against US fighters. It was an extremely dangerous mission. Now two men, Lieutenant Hashizume and Ensign Shosuke Sasao, would have to fly it.