Submerged Cultural Resources Study:
USS Arizona and Pearl Harbor National Historic Landmark
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Chapter II: Historical Record

The Japanese Midget Submarines at Pearl Harbor

The Mission

As plans and preparations were being made in 1941 for Japan's Hawaii Operation, Admiral Isoroku Yamamoto decided that a special submarine force would attack in concert with carrier-borne aircraft at Pearl Harbor.

The development of submersible craft as weapons for naval warfare began with the construction of small vessels. From Bushnell's "Turtle" and Capt. Horace Lawson Hunley's Confederate DAVID, through John Holland's FENIAN RAM and HOLLAND I, submersibles grew larger, achieving greater size and effective use by the time of the First World War. The success of the "submarine" during the war led to increased programs of development and construction by various nations. In Japan, submarine development included "midget" submarines, and "while some scoffed at the potential of small undersea craft, others were deadly serious in a belief in their capability of dealing destructive blows to the enemy." (Stewart 1974:55). In 1933 Capt. Kishimoto Kaneji, I.J.N., designed two torpedo-shaped midgets as auxiliary weapons to be carried by fast surface vessels. Built in 1934 at Kure Navy Yard and known as "A-Hyoteki" or "A-Target," these vessels, with conning towers fitted as a result of experimentation, led to a later version, "A-Hyotelei," wherein two submarines, HA. 1 and HA. 2, were built in 1936. The midget program, operating under stringent security, commenced in earnest in 1938 as Ourazaki and Kure DY began the construction of 49 Type A vessels, HA. 3 through HA. 52. Among the vessels built during this initial burst of construction was HA. 19, which would later participate in the attack on Pearl Harbor. The beginning of the Second World War led to increased midget construction, including Type-A, Type-B, Type-C and Type-D boats, several experimental prototypes, and KAITEN-type manned torpedoes (Stewart 1974:55; Jentschura, Jung and Mickel 1986:183-184).

Following Admiral Isoruko Yamamoto's determination to attack the United States Pacific Fleet at Pearl Harbor as the opening blow of a war with the United States, military and naval planners began assembling the plan for the attack, which was designated "Operation Hawaii." Initially conceived as an air strike, the plan was modified to combat test the hitherto untested Type A midget submarines. The crews of the midgets, readying for war but not yet knowing their target, were notified in mid-October 1941 to concentrate their training on Pearl Harbor and Singapore, while the Sixth Submarine Fleet's large submarines were modified to carry the midgets piggy-back across the Pacific. Doubts about using the midget submarines plagued the Japanese planners, and as late as November 14, the final decision to employ them had not been made. On November 18, 1941, the mother submarines, each with a midget directly aft of the conning towers and attached to the deck by steel belts, departed Kure Navy Base for Pearl Harbor (Prange, Goldstein and Dillon 1981). Each midget carried two crew men and two torpedoes. Each was 81 feet long, 6 feet in diameter, and powered by a 600-horsepower electric motor. The motor was generated by 224 short-lived Type D batteries, but the batteries could not be self-recharged: Thus the cruising range was limited to less than 100 miles.

Five I-class fleet submarines, I-16, I-18, I-20, I-22 and I-24 of the First Submarine Squadron, Sixth Submarine Fleet, each carrying a Type A midget, were designated as the "Special Attack Force." The midget submarines' mission was to covertly slip into Pearl Harbor, wait until the attack, and then each launch their two torpedoes. They would then navigate submerged, counterclockwise around Ford Island, escape and meet up with their mother subs 7 miles west of Lanai Island. Reaching their destination on December 5, 1941, the five submarines fanned out in their deployment pattern off Pearl Harbor, closing to within 10 miles of the harbor entrance (Stewart 1974:57; Prange, Goldstein and Dillon 1988:49).

midget-sub crewmen
Figure 2.43. "The Nine Young Gods." Nine of the 10 midget-sub crewmen that took part in the Pearl Harbor attack. Conspicuous in his absence is the one survivor who was captured.
(NPS: USAR Collection)

The first midget submarine launched was from I-16. Manned by Ensign Masaharu Yokoyama and Petty Officer 2nd Class Tei Uyeda, the midget left at midnight. At 1:16, I-22 released the midget commanded by Lt. Naoji Iwasa, leader of the midget submarines. At 2:15 I-18 launched the third midget, that of Ensign Shigemi Furuno and Petty Officer 1st Class Shigenori Yokoyama. At 2:57, the fourth midget submarine was launched from I-20. This midget was commanded by Ensign Akira Hiroo accompanied by Petty Officer 2nd Class Yoshio Katayama. Last to launch was HA. 19 from I-24 at 3:33. Commanded by Ensign Kazuo Sakamaki and Chief Warrant Officer Kiyoshi Inagaki, HA 19 slipped off the deck of I-24 about 10-1/2 miles off Pearl Harbor and headed for the lights of Honolulu (Prange, Goldstein and Dillon 1981).

One of the fears of the attack planners was that the presence of the submarines would give away the Japanese intent. The fear was justified; however, U.S. forces did not understand the significance of sighting a submarine within the Pearl Harbor defensive zone until too late. The first midget submarine sighting was by the minesweeper USS CONDOR. At 3:42, 1-3/4 miles south of the Pearl Harbor entrance buoys, CONDOR spotted a periscope. The minesweeper notified the destroyer USS WARD, whose commander, Capt. William Outerbridge, searched without success until 4:45. The next sighting came an hour later. At 5:45, the USS ANTARES' crew, towing a target into the harbor, spotted a submarine following them in. The submarine's conning tower was exposed. A seaplane spotter dropped smoke pots off the submarine at 6:33, giving the WARD a fix. At 6:37 the WARD spotted the midget behind the ANTARES at 12 knots, obviously making a run for the harbor. Captain Outerbridge made a decision in just three minutes to attack. Sounding general quarters at 6:40, the WARD's engines surged full ahead as the gun crews loaded the deck guns. No. 1 gun opened fire at 6:45 and missed; immediately No. 3 gun fired, hitting the submarine at the conning tower's junction with the hull. The submarine heeled to starboard, slowed and sank. The WARD depth-charged the sinking vessel as it plunged 1200 feet down, and at 6:46 ceased fire. The United States Navy, which had traded shots with German U-Boats in the Atlantic and probably had sunk one, had just made its first confirmed kill in World War II, and the opening shots of the war preceded the air attack at Pearl Harbor by an hour. Outerbridge sent a message to CINCPAC at 6:51; "We have dropped depth charges upon sub operating in defensive sea area." An amended message was sent at 6:53: "We have attacked, fired upon, and dropped depth charges upon submarine operating in defensive sea area." Advance warning of an attack was not heeded, and at 7:50 the first wave of Japanese planes hit Pearl Harbor and other military bases on the island of Oahu (Prange, Goldstein and Dillon 1981).

midget sub being removed
Figure 2.44. One of the midget subs being removed from the bottom in 1968.
(NPS: USAR Collection)

At 8:17 the destroyer USS HELM's crew spotted a midget submarine hung up on the starboard side of the channel entrance. The submarine submerged but immediately popped up again at 8:18. The HELM fired upon the submarine, but it submerged again and slipped away. Meanwhile, inside the harbor, the USS ZANE, a minesweeper, spotted another midget submarine 200 yards aft of the MEDUSA at Berth K-23 at 8:30. The ZANE's report was noted, and at 8:32, CINCPAC sent out the alert "Japanese submarine in harbor." The seaplane tender CURTISS opened fire at a midget submarine inside the harbor at 8:36; the submarine fired a torpedo at the tender that missed. As the CURTISS brought additional guns to bear, the destroyer USS MONAGHAN spotted the submarine and ran full speed toward it in an attempt to ram. Just as the submarine surfaced, damaged by the CURTISS's shot to the conning tower, the MONAGHAN struck it a glancing blow as a second torpedo passed harmlessly beneath the destroyer and exploded on the bank. Dropping two depth charges, the MONAGHAN finished off the midget submarine (Prange, Goldstein and Dillon 1988:234-236).

Outside the harbor, other Navy vessels were depth-charging numerous submarine "contacts." At 10:04 the cruiser USS ST. LOUIS was missed by two torpedoes. Spotting a midget submarine, the crew fired upon and apparently sank it. The WARD, whose crew claimed first blood at Pearl Harbor, depth charged four separate "contacts" between 10:20 and 11:50. At 17:15, the USS CASE depth charged another target. Meanwhile, aboard the mother submarines, the Special Attack Force awaited news from its comrades. At 22:41, I-16 received a radio message from the midget submarine commanded by Ensign Yokoyama, "successful surprise attack." (Prange, Goldstein and Dillon 1988:311-313). According to historian Gordon W. Prange:

On this slender evidence the Japanese Navy concluded that at least three midget submarines had penetrated Pearl Harbor and, after the air raid, had inflicted severe damage, including the destruction of a capital ship. Quickly the word spread that the minisubs had sunk the ARIZONA. During the spring of 1942, the Japanese Navy released this to the press, and the midget submariners were venerated as veritable gods, to the resentment of the fliers, who knew exactly when and under what circumstances the ARIZONA had exploded (Prange, Goldstein and Dillon 1988:361).

midget sub HA. 19 beached
Figure 2.45. Japanese midget submarine HA. 19 beached at Bellows on the northern or windward side of Oahu. Photo by Signal Corps.
(NPS: USAR Collection)

While the submariners were venerated as the "heroes of Pearl Harbor" by Japanese and German propagandists, the actual record was dismal; the midget submarines did not achieve any success at Pearl Harbor. On the evening of December 7 and 8, the mother I-submarines met at the Lanai Is land rendezvous, but the midgets did not return. The last contact was by radio at 1:11 on December 8 when I-16 heard from Ensign Yokoyama once again. By that time, Yokoyama and his crewman, and Ensign Kazuo Sakamaki and Chief Warrant Officer Inagaki in HA. 19 were probably the last midget submariners alive.

Designated "Midgets A through E" by the United States Navy (for the order in which the U.S. encountered them), the midget submarines have been gradually accounted for. "Midget A,"' sunk by the USS WARD, has possibly been located in 850 feet of water by a joint U.S. Navy/National Park Service submerged cultural resources survey of Pearl Harbor in the Summer of 1988. Immediately after the attack, "Midget B," rammed and sunk by the MONAGHAN, was raised and buried in landfill at the Submarine Base in 1942. Subsequently disinterred and then reburied again, the midget still lies in coral and sand fill as a permanent part of the base it attacked. "Midget C," HA. 19, washed ashore on December 8 and was captured. "Midget D" was located by Navy divers on a training exercise in 1960. Raised, it was returned to Japan and is now a memorial at the Submarine School at Eta Jima. Only "Midget E"'s location is unknown; if Ensign Yokoyama slipped out to sea in a failed attempt to rendezvous with the mother subs, E" might hold his remains (Stewart 1988).

conning tower of midget sub
Figure 2.46. Conning tower of Japanese midget submarine HA. 19.
(NPS: USAR Collection)

Last Updated: 27-Apr-2001