Ordeal of Mogami and Mikuma
I.168's Attack on Yorktown
The End

I.168 (ex 1.68) in a pre-war photo.

Based upon the information received on June 5 from Chikuma's No.4 scout and planning on making first contact at dawn on June 6, CDR Yahachi Tanabe moved I.168 into position. At 0410, a lookout spotted a "black spot starboard ahead!" Within a few moments Tanabe identified Yorktown 20,000 meters away. Tanabe spotted the first two destroyers at 0600, so he submerged and slowed to three knots. As he closed, he counted a total of seven destroyers circling about 1000 meters away. (Actually, there were only six. The seventh was the minesweeper Vireo, which had taken Yorktown in tow.)

Five minutes after Tanabe's sighting, the salvage party re-boarded Yorktown in the continuing effort to save the ship. Some of the party started their work by extinguishing the last of the fires (in the rag storage compartment) and determine the extent of the damage below the waterline. Others began to get rid of weight on the port side and push those planes that were left on board overboard in an effort to correct her list. CAPT Buckmaster ordered Hammann back along side to provide houses to pump water from the stricken carrier and to provide food and water for the salvage party.

Tanabe's next periscope observation was made at 15,000 meters, prompting him to order his crew to prepare for depth charges. It was also during this and subsequent observations that Tanabe noticed Yorktown was drifting (she was actually being towed), but he couldn't tell at what direction or speed. He did know that the movement of the carrier meant he would have to attack from starboard instead of the port attack he had hope to carry out. So he put the scope down and steered by chart and sound for the next few hours.

At 1237 Tanabe raised the periscope and found he was only 500 meters away from Yorktown, so close that his torpedoes would travel under the target. He also was now well inside the circle of destroyers. So he lowered the periscope, moved away from the carrier, again navigated through the labyrinth of destroyers.

When Tanabe looked again, he was 1500 meters from Yorktown, which was just about the perfect distance. At about 1330, I.168 launched two, two torpedo spreads. Monaghan spotted the torpedoes first, and used the talk between ship (TBS) circuit to warn Yorktown. Next to spot the torpedoes was the helpless Hammann, still moored next to the carrier, less than 1,000 yards off the starboard beam. The alarm was sounded on Yorktown at 1335- machine guns blazing- as the first torpedo struck the Hammann and broke her back. The next two passed under the destroyer and struck Yorktown at "frame 85 on starboard side." The fourth torpedo passed astern of the carrier.

Until the time of I.168's attack, it looked very much like Yorktown would be saved. The fire in the rag storage compartment had been extinguished. Pumps had transferred water from the third deck on port side to the fourth deck on starboard, effectively counter flooding the carrier in spite of her lack of power. Other pumps in the aft engine room were removing water from that compartment and depositing it overboard. Still more pumps aboard Hammann transferred water from the destroyer into Yorktown's empty starboard fuel tanks. All of this hard work, plus the lessening of topside weight, had reduced Yorktown's list from 26 to 22 degrees.

Hammann sank in three minutes. LCDR Arnold E. True, Hammann's CO, broke a rib and lost his wind. Therefore it was her XO, LT Ralph W. Elden, that ordered all hands to abandon ship. Misery for her crew, and Yorktown, was added when her depth charges went off at three levels. The depth charges and torpedo killed nine officers and seventy-two crewmen, wounded several others and weakened Yorktown's hull further. Most of the work done by the salvage party over the last two days was undone in a few horrible seconds. Water began pouring into the ship through the new holes in the hull. The effect actually lessened the carriers list futher- to about 17 degrees. Fearing Yorktown might sink rapidly, Vireo order the tow line cut and doubled back to begin rescuing the survivors.

Depth charging began about 1335 by Gwin, Monaghan and Hughes, with I.168 heading straight for Yorktown. Balch and Benham commenced rescuing the crew of Hammann and the salvage party. For the first hour or so, the destroyers dashed around like angry bees, with their depth charges continuing to damage Yorktown's tender hull. It was not until about 1445 that they first stung, as two depth charges shook Tanabe and his crew. For the next two hours, I.168 battled American destroyers, decreasing oxygen, decreasing power, and chlorine gas. At 1640, when I.168 began to surface, Tanabe decided to let her. He ordered:

Prepare the guns and machine guns for firing. Surface quickly and open fire.

As his boat came to the surface, Tanabe quickly headed to the bridge, only to find three destroyers circling 10,000 meters away. American records show these ships as Benham, Monaghan and Hughes. Tanabe saw no other ships, and concluded he sank Yorktown. After a few minutes the destroyers spotted the sub and turned towards it. With the batteries exhausted, there was nothing to do but try to run as long as possible. He also wired the Rengo Kantai:

We sank Yorktown

Tanabe and his crew, however, was in quite a dilemma. The electric motor could not be used and he didn't have enough oxygen to submerge, and lookouts kept reporting the destroyers were closing. Soon shells began to splash in the water around the sub. An inquiry by Tanabe into the amount of air in the tanks brought a response of "eighty kgs". He immediately submerged his boat. More good news soon followed from engineering:

The motor can be used.

In addition, the depth charging became more and more distant. At 1850, Tanabe triumphantly surfaced his boat. His crew had not eaten or drank for thirteen hours, except for the traditional victory cup at the sound of the torpedo explosions. He and his crew could now celebrate the sinking of an aircraft carrier.

Contrary to Tanabe's initial report, Yorktown had not yet sunk. In fact, as discussed earlier, the two torpedoes corrected Yorktown's list from 26 to 17 degrees. Buckmaster informed CinCPAC of the submarine attack and optimistically stated "with help we will bring her in..." In addition, he requested air cover. Although his salvage party was removed, Buckmaster hoped to start his work again on the morning of June 7. At 2000, Balch, Benham, Gwin and Vireo began circling Yorktown, to be joined by Monaghan and Hughes after midnight. Workers did not lose hope until nearly dawn, and Yorktown, according to CAPT Buckmaster's report to CinCPAC, "turned over... and sank in about 3000 fathoms of water..." at 0458 on June 7. With the end of Yorktown, her escorts set off for Pearl Harbor, and the most important battle to date had come to an end.

One final problem needed to be overcome before I.168 could get back to Japan. She didn't have enough fuel to get back! The Japanese were so confident of victory that Tanabe was told he could refuel at Midway after the battle. By using only two engines on the trip, I.168 made it back with 800 kgs. of fuel to spare.

I.168 Specifications

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