On December 7, 1941, forces of the Imperial Japanese Navy attacked the United States’ Pacific naval Anchorage, at Pearl Harbor. President Franklin Delano Roosevelt addressed a joint session of Congress the following day, requesting a declaration that, since the attack, a state of war had existied between the United States, and Japan. Three days later, Nazi Germany declared war on the United States, reciprocated by an American declaration against Nazi Germany, and their Italian allies. A two-years long conflict in Europe, had become a World War.
In the months that followed, the United States ramped up its war capacity, significantly. Realizing this but having little information, the Imperial Japanese Navy (IJN) determined to visit Pearl Harbor once again, to have a look around.
For the IJN, this was an opportunity to test the new Kawanishi H8K1 “Emily” flying boat, an amphibious bomber designed to carry out long distance bombing raids. So it was that a second, albeit smaller attack was launched against Pearl Harbor.
The IJN plan was complex. This, the first Kawanishi H8K1 operation in Japanese military service, involved a small formation of flying boats to be sent to Wotje Atoll in the Marshall Islands, from there to stage the long-range attack. The five flying boats would be loaded with four 550lb bombs apiece and flown to French Frigate Shoals northwest of Oahu, there to rendezvous with three Japanese submarines, waiting to refuel them. Ten miles south of Oahu, the 356’ diesel-powered submarine I-23 was to hold watch over the operation, reporting weather and acting as “lifeguard” in case any aircraft had to ditch in the ocean.
After refueling, the bomber – reconnaissance mission would approach Pearl Harbor and attack the “10-10 dock”, so-called because it was 1,010 feet long and a key naval asset for the US Pacific Fleet.
If successful, this would be an endurance mission, one of the longest bombing raids ever attempted, and carried out entirely without fighter escort. The mission was designated “Operation K”, and scheduled for March 4, 1942.
As it turned out, the raid was a “comedy of errors”, on both sides.
Things began to go wrong, almost from the beginning. I-23 vanished. To this day nobody knows where the submarine went. American forces reported several engagements with possible subs during this time frame. Maybe one of those depth charges did its job. It is equally possible that, unknown to the Imperial Japanese Navy, I-23 was involved in an accident, lost at sea with all hands.
As it was, only two of the new flying boats were ready for the operation, the lead plane (Y-71) flown by Lieutenant Hisao Hashizume, and his “wingman” Ensign Shosuke Sasao flying the second aircraft, Y-72.
The staging and refueling parts of the operation were carried out but, absent weather intelligence from the missing I-23, the two-aircraft bombing formation was ignorant of weather conditions over the target. As it was, a thick cloud cover woud leave the Japanese pilots all but blind.
On the American side, Captain Joseph J. Rochefort, USN, worked in the Combat Intelligence Unit, tasked with intercepting enemy communications and breaking Japanese codes. US code breakers had intercepted and decoded Japanese radio communications prior to the attack of four months earlier, but urgent warnings were ignored by naval authorities at Pearl Harbor.
Once again, Rochefort’s team did its job and urgent warnings were sent to Commander in Chief Pacific (CINCPAC) and to Com-14. Incredibly, these warnings too, fell on deaf ears. Rochefort was incredulous. Years later, he would describe his reaction, at the time “I just threw up my hands and said it might be a good idea to remind everybody concerned that this nation was at war.”
American radar stations on Kauai picked up and tracked the incoming aircraft, but that same cloud cover prevented defenders from spotting them. Curtiss P-40 Warhawk fighters were scrambled to search for the attackers, while Consolidated PBY Catalina flying boats were sent to look for non-existent Japanese aircraft carriers, assumed to have launched the two bombers.
Meanwhile, the two Japanese pilots became confused, and separated. Hashizume dropped his bombs on the side of Mt. Tantalus, about 1,000 ft. from nearby Roosevelt High School. Hashizume’s bombs left craters 6-10 ft deep and 20-30 ft across on the side of the extinct volcano. Sasao is presumed to have dropped his bombs, over the ocean.
A Los Angeles radio station reported “considerable damage to Pearl Harbor”, with 30 dead sailors and civilians, and 70 wounded. Japanese military authorities took the broadcast to heart, and considered the operation to have been a great success. Talk about ‘fake news’. As it was, the damage was limited to those craters on Mt. Tantalus, and shattered windows at Roosevelt High.
The United States Army and the US Navy blamed each other for the explosions, each accusing the other of jettisoning munitions over the volcano.
The IJN planned another such armed reconnaissance mission for the 6th or 7th of March, but rescheduled for the 10th because of damage to Hashizume’s aircraft, and the exhaustion of air crew. The second raid was carried out on March 10, but Hashizume was shot down and killed near Midway atoll, by Brewster F2A “Buffalo” fighters.
A follow-up to Operation K was scheduled for May 30, but by that time, US military intelligence had gotten wise to the IJN meet-up point. Japanese submarines arriving at French Frigate Shoals found the place mined, and swarming with American warships.
In the end, the Imperial Japanese Navy was unable to observe US Navy activity, or to keep track of American aircraft carriers. Days later, this blindness would have a catastrophic effect on the Japanese war effort, at a place called Midway.