Free War Beneath the Waves by Don Keith

first patrol with the new weapon bolted to her deck—and Charlie Rush’s first patrol as her engineer— Thresher attacked a three-thousand-ton freighter at the south end of the Makassar Strait. She did it using only the deck gun.
    They drove the ship into shallow water and she probably sank there. Unfortunately, though, the captured Japanese records would not confirm it after the war, so Thresher received no credit for the unusual accomplishment.
    No matter. Millican and his pleased squadron commander, Admiral Lockwood, claimed the largest ship sunk to that point in the war solely by the use of a deck gun. Millican was rapidly heading for legendary status, right along with the other submarine “aces.”
    On the day after Christmas 1942, Thresher was patrolling a sea-lane between Surabaya and the main Japanese base in Singapore. At midafternoon, as they made regular stops to raise the periscope and look around, the watch officer spotted smoke on the horizon. The smoke almost certainly signaled a ship, steaming along and ripe for the taking. Any ship was a potential target. Millican ordered them to the surface so they could move more quickly to a point where they could intercept, observe, and possibly attack.
    While submerged, the World War II-era submarine could travel only about eight or nine knots, and even then only for short periods of time or they risked using up all their battery power. They also had to come to an almost complete stop to use the periscope. On the surface, though, they could make as much as twenty knots and were almost as seaworthy as many surface vessels.
    Even so, this ship was moving faster than that and there was a good chance she was about to slip away. Thresher had to do some maneuvering to flank the target ship, which was zigzagging specifically to try to avoid a submarine attack. That alone confirmed for Millican that this was a worthy target. If she was worried enough about a submarine attack to zig and zag, she carried something valuable enough for him to take the time and effort to sink her.
    Thresher finally drew close enough to see the ship’s masts and line up for an attack. Darkness was about to fall.
    In the conning tower, Millican peered through the optics of the periscope at the ship they had run down. There was a smile on his face. Easy pickings. There was no way they could miss bagging this game.
    He gave the command to fire the torpedoes.
    Thresher fired three torpedoes at what amounted to point-blank range. They waited for the flash and fire and boom. The men in the conning tower watched their skipper’s face. The flash would often reflect through the periscope on his cheeks. Or his body language and facial expression would tell them how good the hit was.
    No explosion. No flash.
    “Sonar, you still hear our fish?” Millican asked. “They still running? No way we missed with all three!”
    “Captain, I heard two clunks,” the sonarman reported. “Two duds.”
    Millican tried to hide his anger, but all the men on duty in the conning tower saw his aggravation. They wisely kept their heads down.
    The target ship steamed on, zigging and zagging, apparently unaware of the close call she had just had. Millican scratched his jaw and pondered his options.
    It would not be the only time they had such disappointing results. On the same patrol, Thresher had a Japanese submarine—an I-boat—in her sights. Such a chance was rare. It is difficult for one submarine to sink another, since both can move vertically in addition to all the other angles a surface ship can take. That made stalking and shooting much more difficult than lining up and firing on a surface target.
    Millican fired two precious torpedoes at the I-boat. One missed and exploded harmlessly on the ocean bottom. The other struck the target squarely against its steel hull, a solid hit, good enough to send her to the bottom.
    It failed to explode.
    “Damn! We clinked them with a clunk!” Millican told the crew around