In the early hours of 4 March 1942, three months after the attack of 7 December 1941, two Japanese Kawanishi H8K flying boats reached Oahu with orders to bomb Pearl Harbor again. The raid, called Operation K, was meant to disrupt the repair of the American fleet and to scout the base. Cloud and the blackout hid the target, and the bombs fell on a hillside above Honolulu and into the sea. Nobody was hurt, but the raid showed the Americans how the Japanese had reached Hawaii, and that knowledge mattered before the Battle of Midway.
A plan to hit the dockyard
The attack of 7 December had wrecked the battleships of the Pacific Fleet, but the shipyard that was repairing and salvaging them kept working. Operation K was meant to disrupt that work by bombing the so-called Ten-Ten dock, named for its length of 1,010 feet, and to see how far the repairs had gone.1
The new Kawanishi H8K flying boats had a very long range, but not long enough to reach Hawaii and return. The plan was to refuel them from submarines at French Frigate Shoals, an atoll in the Northwestern Hawaiian Islands, about 560 miles from Honolulu. According to the Honolulu Advertiser, which cites the historian Steve Horn, American codebreakers in Hawaii warned higher command of signs that Japanese seaplanes would scout Pearl Harbor by way of French Frigate Shoals, but nothing was done.2
The flight of 3 and 4 March
Station HYPO notes that the plan called for five aircraft, but only two were ready. Lieutenant Hisao Hashizume led the mission, with Ensign Shosuke Sasao flying the second plane, and each carried four bombs of about 550 pounds. They took off from Wotje Atoll in the Marshall Islands, which Stars and Stripes dates to 3 March, flew about 1,900 miles to French Frigate Shoals and took on fuel from waiting submarines before covering the last 560 miles. A submarine that was meant to guide them near Oahu, I-23, had been lost at sea some time after 14 February, Station HYPO adds.3
Radar picked up the two planes as they approached, and fighters were scrambled. In the dark and the cloud, and without airborne radar, they could not find the flying boats.4
Bombs on Tantalus
The same cloud blinded the Japanese crews, and the island below was blacked out. The two planes became separated in poor radio conditions. At about 2 a.m. Hashizume dropped his bombs on the forested slopes of Tantalus, above Honolulu, not far from Roosevelt High School, whose windows were shattered. A man who had lived nearby as a boy told the Honolulu Advertiser that the last crater was about 6 feet deep and 30 feet wide. Sasao's bombs probably fell into the sea. No one was hurt.5
Both flying boats got back to the Marshall Islands. Japanese radio and newspapers repeated a claim, said to come from a Los Angeles broadcast, of heavy damage at Pearl Harbor with 30 dead and about 70 wounded, the Honolulu Advertiser reports, citing Horn. Stars and Stripes calls the flight the longest-distance bombing run of the war. A second raid planned for 6 March was called off.6
Why it mattered at Midway
The raid did almost no damage, but it gave its method away. From the radar plots American analysts worked out that the planes had refueled from submarines at French Frigate Shoals. Stars and Stripes quotes the Pacific Aviation Museum historian Burl Burlingame as saying a destroyer was then kept at the atoll for the rest of the war.7
Before the attack on Midway the Japanese planned to repeat Operation K about 30 May to find out where the American carriers were. The flight never took place, and Admiral Chuichi Nagumo did not learn of the carriers that surprised his fleet at Midway in June. Read more in our article on the Battle of Midway and our account of the attack on Pearl Harbor.8
Note: the time of the bombing is given as about 2 a.m. local time.
