I-168: The submarine that sank the aircraft carrier USS Yorktown


The Battle of Midway in June 1942 is famous for several reasons. Chief among them, perhaps, is the sinking of four Imperial Japanese Navy aircraft carriers – the Akagi, kaga, Sōryūand Hiryu – which turned the tide of the Pacific theater of operations during World War II. There’s also the way the battle made it clear that carrier plane had replaced “capital ships”, i.e. battleships, as the predominant armament system of naval warfare.

What is not as well known is the role that submarines played in this epic battle. On the American side, the USS Nautilus inadvertently played a role in the detection of the IJN aircraft carrier fleet. Meanwhile, the biggest damage inflicted by the IJN during Midway was caused by a submarine, the I-168who sank the USS aircraft carrier Yorktown (CV-5) and the destroyer USS Hammann (DD-412).

Not U-Boats, but I-Boats

The I-boats were the full-size submarines of the IJN fleet (meaning they displaced at least 1,000 pounds). The designation does not correspond to the U-boat (Unterseeboot) designation of German Kriesgsmarineit was rather the transliteration of a character that meant the first of a series, stemming from the 11th century poem Iroha which was used to denote the alphabetical order of Japanese characters, or cana. “I“meant the largest or first class of submarines, followed by class B from 500 to 999 tons”Ro“the boats, and finally the Class C”Ha“boats, midget submarines with a displacement of less than 500 tons.

Submarine service was a highly desirable position in the IJN, especially for enlisted sailors. The reason being, as Keith Wheeler notes in his excellent book War under the Pacific (part of the Time Life Books WWII series), the brutal discipline for which the Imperial Japanese Army was infamous was not applied as rigidly to submarine crews, allowing for a more relaxed working environment that fostered a more genuine sense of camaraderie. How brutal was the discipline of the IJN, you might be wondering? In the Japanese army of World War II, a commissioned officer could hit an enlisted man at any time and for any reason. As World War II historian Robert M. Citino has noted:

You could be beaten nearly to death for almost any reason: not greeting smart enough, missing a button on your shirt, nonchalant attitude. Not drawing attention to the mention of the Emperor’s name was a grave offense in this world, and some particularly sadistic officers seemed delighted to mention the Emperor only to catch their men napping..”

The I-168 had her keel laid on June 18, 1931, was launched on June 26, 1933 and commissioned on July 31, 1934. She was then decommissioned on December 12, 1938, and returned to service May 1, 1939. She had a length of 322 feet, a surface speed of 23 knots and a diving speed of 8.2 knots. Being one of the Kadai class boats, I-168 wielded six torpedo tubes – four forward and two aft – one 10cm/50 Type 88 deck gunand a 13.2mm machine gun for AA protection.

During the Battle of Midway, I-168 was skippered by Lt. Comm. Yahachi Tanabe.

Half way mission

Of course, the sinking of the Japanese submarine Yorktown was not a solo act. The historic and beloved carrier under the command of Captain Elliott Buckmasterr had already been badly damaged by Aichi D3A1 “Val” dive bombers and Nakajima B5N “Kate” torpedo bombers launched from the deck of the Hiryu. Notice, it was after Yorktown had undergone an almost miraculous repair after the damage it had suffered during the Battle of the Coral Sea the preceding month. Yorktown was being towed by the fleet tug USS Vireoand the Hammann had attached along the starboard side of the carrier to provide fire and rescue assistance. Thus was the setting for a double tragedy for the US Navy and a double triumph for the IJN. (Although obviously the U-boat’s triumph would pale in comparison to the overall defeat Japan suffered in the battle.)

At 1:30 p.m. on June 5, 1942, Tanabe fired a salvo of four torpedoes. The first torpedo hit Hammann, which sank just four minutes later. Eighty-one of the destroyer’s 241 crew perished, a death toll that might have been lower had it not been for the secondary explosions from the ship’s depth charges. The second and third torpedoes hit Yorktown on her starboard side below her deck, while the fourth tin fish missed aft.

Tanabe dived his boat 200 feet to prepare for a retaliatory depth charge attack from the surviving destroyers. In 64 minutes, I-168 endured 40 depth charges which inflicted severe damage, but the sub was eventually able to return safely to base at Yokosuka.

Meanwhile, at 7:01 a.m. on June 7, Yorktown eventually sank, with a total of 141 of her officers and enlisted men killed in action. All surviving USN ships present to witness the sinking are said to have lowered their flags at half mast in salute, and all hands that were upside down stood to attention with their heads uncovered, many with tears in the eyes.

Midway Maritime Memorials

The US Navy ended up taking revenge on the I-168 on July 27, 1943, when one of the American submarines, the USS Prank, sank her in the Bismarck Sea – 60 nautical miles off New Hanover Island – with a four-torpedo salvo. All 97 men aboard the Japanese submarine perished. To my knowledge, the wreckage of the ship has not yet been found. (If any of our readers know otherwise, please post in our comments section!)

USS Yorktown lies 5,500 meters below the surface. The remains of this great old lady were discovered on May 19, 1998 by Dr. Robert D. Ballardwho is of course most famous for finding the wreck of the RMS Titanic. Meanwhile, HammannThe wreckage of has yet to be found, but it should presumably be in the same general area as Yorktown.

Christian D. Orr is a former Air Force officer, federal law enforcement officer, and private military contractor (with assignments in Iraq, United Arab Emirates, Kosovo, Japan, Germany and the Pentagon). Chris holds a BA in International Relations from the University of Southern California (USC) and an MA in Intelligence Studies (Terrorism Studies Concentration) from the American Military University (AMU). It was also published in The Daily Torch and The Journal of Intelligence and Cybersecurity. Last but not least, he is a Companion of the Order of United States Naval Order (WE).


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