Yahachi Tanabe, former Lieutenant Commander in the Imperial Japanese Navy, explains how he sank the Yorktown at Midway:
Abaft my beam, each about 1,000 yards distant, were a pair of American destroyers, one to port, one to starboard. I-168 had safely pierced the protective screen of escorts; I could now give the order to fire.
Then I took another look. Yorktown and her hugging destroyer filled my periscope lens. I was too close! At that moment I estimated my range at 600 yards or less. It was necessary to come around and open up the range.
What I had to do now was try to escape detection by those destroyers above us and get far enough away so that my torpedoes, fired from a 60-foot depth, would have enough running space to stabilize themselves at a 19-foot depth for hitting. Whatever was the reason, enemy sound detectors could no longer be picked up by our equipment, I knew the destroyermen above were not asleep.
I kept I-168 in a right-hand circle, easing the rudder a little so that I could return to my original track at a point about one mile from Yorktown. I didn’t dare put up the periscope until the compass showed us back on our original course. So I concentrated instead on a torpedo tactic I wanted to use. Though some submarines in 1942 had Model 95 torpedoes — underwater versions of the very powerful Model 93 “Long Lance” used on surface ships — my torpedoes were an older type. Model 95′s had 991-pound warheads, mine had 446-pound ones. So I planned to make two torpedoes into one.
If I followed the usual procedure and fired my four torpedoes with a two-degree spread, they would cover six degrees. But I wanted very badly to deprive the Americans of this carrier. I intended to limit my salvo to a two degree spread I would fire No.1 and No.2 first, then send No.3 and No.4 in their wakes, on the same courses. That way, I could achieve two large hits instead of four small ones. I could thus deliver all my punch into the carrier’s midsection, rather than spread it out along her hull.
When I was back on my approach course, I took another look, and wagged my head at how the destroyers still seemed unaware of us. Either they were poor sailors, had poor equipment, or I-168 was a charmed vessel. At a range of 1,200 yards, my periscope up, I sent my four torpedoes away as planned. I did not lower the periscope then, either. The wakes of my torpedoes could be seen, so their source could be quickly established. And, if I-168 was going to die, I at least wanted the satisfaction of seeing whether our fish hit home.
Less than a minute later we heard the explosions. “Banzai!” someone shouted. “Go ahead at full speed!” I ordered, then, “Take her down to 200 feet!” My conning tower officers were surprised when I ordered speed cut back to three knots a short time afterward, but by that time we were where I wanted to be, directly beneath the enemy carrier. I didn’t think she would sink at once, so had no fear of her coming down on us. And one of our torpedoes had run shallow and hit the destroyer alongside Yorktown. There would be men in the water. Her destroyers wouldn’t risk dropping depth charges for awhile, for fear of killing their comrades. Meanwhile, I hoped to creep out of there. I ordered left rudder, and tried to ease away at three knots.
My plan didn’t work.