Yokosuka Naval Arsenal, Japan October 8, 1944

Shinano was the largest aircraft carrier ever built until the early 1960s. Her keel was laid down on May 2, 1940, at the Yoko­suka Naval Arse­nal south of Tokyo. She was launched 4½ years later on this date, Octo­ber 8, 1944. The carrier was to have been the third of the legen­dary Yamato-class super battle­ships, whose keels were laid down in the late 1930s. In the wake of the Battle of Mid­way (June 4–7, 1942) and calam­i­tous loss of four Japa­nese fleet carriers (Akagi, Kaga, Soryu, and Hiryu carrying 248 com­bat air­craft), the Imperial Japa­nese Navy ordered the hull, 45 per­cent com­plete, con­verted to an air­craft carrier. The con­ver­sion caused the battle­ship’s main deck to become Shinano’s hangar deck for half the num­ber of air­craft aboard a typical Japa­nese fleet carrier. A flight deck was built on top of that deck to launch and recover planes. Shi­nano’s role was that of a heavily armored support air­craft carrier. Its hangar held its own air group of 18 fighters, 18 torpedo-dive bombers, and 6 recon­nais­sance air­craft with room for upward of 120 replacement aircraft.

At 69,000 tons Shinano’s displacement was several thou­sand tons less than her two half-sister battle­wagons, Yamato and Musashi. In part that was due to Shi­nano’s main armor belt being two-thirds less thick as well as the absence of the 9 devas­ta­ting 18‑inch cannon of her half-sisters. Other than its own air­craft, Shi­nano’s arma­ment con­sisted of 16 five-inch anti­air­craft guns, 105 25mm anti­air­craft machine guns, and 12 mul­tiple rocket launchers with 4.7‑inch unguided anti­air­craft rockets. With an esti­mated range of 10,000 nau­ti­cal miles, Shi­nano was to be crewed by 2,400 officers and enlisted men.

Shinano was commissioned on November 19, 1944, but an acci­dent the pre­vious month pre­vented her from begin­ning serious sea trials until Novem­ber 28. On Octo­ber 8, launch day, a dry dock gate buckled, allowing a surge of sea­water to smash the bow of the 872‑foot-long ship against the dock’s head­wall three times. Repairs took 2½ weeks, followed by a partial fitting-out and more sea trials.

Meanwhile, on November 24, 1944, the United States Army Air Forces launched its first strike of Boeing B‑29 Super­for­tresses from the Mari­anna Islands toward Tokyo. The target was an air­craft engine plant in the arse­nal sec­tor of the cap­i­tal north of the ship­yard where Shi­nano was build and berthed. A U.S. recon­nais­sance fly-over added to the pres­sure that the INJ order Shi­nano to a safer loca­tion. Late on Novem­ber 28, 1941, Shi­nano steamed south for Kure Naval Arse­nal, Hiro­shima, Japan’s single-largest naval base, not­with­standing that her water­tight doors had yet to be installed, holes in the com­part­ment bulk­heads for cables, venti­la­tion ducts, and pipes were still unsealed, and fire mains and bailing sys­tems lacked pumps. Aboard was a com­ple­ment of 2,175 crew­men, plus 300 ship­yard workers and 40 civil­ians engaged in making Shinano, in due course, shipshape.

Shinano steamed right into the arms of the USS Archer­fish. Two hours and 48 minutes after departing Yoko­suka’s ship­yard with a trio of es­corting destroyers, the quartet lit up Archer­fish’s radar screen. Like­wise Shi­nano, as she zig­zagged her way south to Kure, had picked up the uniden­ti­fied sub. Cap­tain Toshio Abe main­tained a tight leash on his screening destroyers, believing the intruder to be a wolf­pack decoy intent on luring away his escorts. At 3:15 a.m., Novem­ber 29, Abe changed course 30 degrees and veered broad­side right into the path of Archer­fish’s 6 loosed Mark 14 tor­pe­does, 4 of which found their mark.

Just shy of 11 a.m. Shi­nano capsized and sank, taking Abe and 1,434 naval men and civil­ians to their deaths 65 miles off the east coast of Honshū Island. Sur­vi­vors num­bered 1,112. Shi­nano’s demise was a well-kept secret. U.S. Pacific Fleet ini­tially cred­ited Archer­fish, skip­pered by Com­mander Joseph F. Enright, with sinking a cruiser (!), then settled on a 28,000ton Hiyō–class air­craft carrier. After the war the record was corrected.

World War II Version of David Meets Goliath: USS Archerfish Versus Shinano, Imperial Japan’s Largest Warship

USS "Archerfish" torpedoes Japanese aircraft carrier "Shinano," November 29, 1944

Above: Artist’s color rendering of the USS Archer­fish’s tor­pedo strike on the Shi­nano on her maiden voyage, Novem­ber 29, 1944. In 8‑second inter­vals 4 war­heads from a vessel 46 times smaller than its prey deto­nated against Shi­nano’s supposedly impreg­nable hull. At first Shi­nano’s offi­cers weren’t unduly worried about the carrier’s surviv­a­bil­ity and believed its destroyer escorts could tow the listing ship, thou­sands of tons of sea­water hea­vier, to a safe sanc­tu­ary. A single attempt was aborted when tow cables snapped. At 10:18 a.m., 7 hours after the attack, the abandon-ship order was sounded. Chaos reigned. Crew­members, con­scripted Korean laborers, and civil­ian pas­sen­gers had not been drilled on escape pro­ce­dures. Nearly 40 minutes later the mor­tally wounded carrier heeled and sank stern-first. Former destroyer com­mander and sur­vi­vor of the crushing Japa­nese defeat at Mid­way, Cap­tain Toshio Abe, was among Archer­fish’s victims. To sup­press news of the carrier’s embar­ras­sing loss, the 1,081 sur­vi­ving offi­cers, petty offi­cers, enlisted men and the 32 civil­ians were iso­lated on the island of Mitsuko-Jima near Kure Naval Arsenal, Shinano’s destination, until January 1945.

"Shinano" sea trials, Tokyo Bay, November 11, 1944USS "Archerfish", "Shinano" killer

Left: This is just one of two photographs ever taken of the bulbous, clipper bow Shinano, which was built secretly at Yoko­suka Naval Arsenal by seques­tered workers under the watch­ful eyes of the Impe­rial Kem­pei secret police. A civil­ian photo­grapher aboard a harbor tug snapped the photo on Novem­ber 11, 1944, during the Shi­nano’s ini­tial sea trials in Tokyo Bay, just north of the ship­yard where she was built. A Boeing B‑29 recon­nais­sance air­craft took the only other photo­graph 10 days earlier. As seen in this photo­graph, much of Shi­nano’s single hangar was open for ven­ti­la­tion pur­poses at both ends as well as for jet­ti­soning burning aircraft or ordi­nance. Its armored flight deck of 3 inches armor plating and 3/4‑inch ordi­nary steel was designed to with­stand a direct hit by a 1,100‑pound bomb. The joints between the main armored belt and the armored bulk­heads below the water­line were sus­cep­ti­ble to leak­age, and Archer­fish’s tor­pe­does hit that joint. Captain Toshio Abe and his offi­cers scorned Amer­i­can tor­pe­does anyway, which had a poor repu­ta­tion even among some U.S. sailors. It took a full hour before Abe realized the gra­vity of his situ­a­tion, but of course Shi­nano’s fate had already been sealed when she crossed paths with the American sub.

Right: USS Archerfish’s fifth war cruise was skippered by Com­mander Joseph Enright. Archer­fish (also Archer-Fish) was a Balao-class submarine named for a fish that kills its victims with a lethal blast of water from below. Enright had pre­viously skip­pered a sub and botched a chance at sinking the air­craft carrier Sho­kaku. He and the Archer­fish’s exe­cu­tive offi­cer, Lt. Cmdr. Bob Bob­czyn­ski, put their heads together to plot the antic­i­pated anti­sub­marine zig­zag course of the faster uniden­ti­fied vessel (Shi­nano). Enright even sent a wire­less mes­sage informing Pearl Harbor of his posi­tion and his inten­tions in the event another Amer­i­can sub was better posi­tioned to inter­cept and sink his target. Just after a quarter past three on the morning of Novem­ber 29, 1944, four of Archer­fish’s six Mark 14 torpe­does tore into Shi­nano’s star­board hull con­taining oilers, engines, steering equip­ment, elec­tronic and com­mu­ni­ca­tion gear, and ammu­ni­tion maga­zines—Enright’s aim could not have been better. Once the exis­tence of Shi­nano was dis­covered, the U.S. Navy cred­ited Enright and the Archer­fish crew with sinking the largest war­ship ever sunk by a sub­marine and awarded the sub’s com­mander the Navy Cross, the depart­ment’s second-highest mili­tary deco­ra­tion for extraor­di­nary hero­ism in com­bat; Archerfish received a Presidential Unit Citation.

Japan’s 69,000-Ton Shinano Inaugurates Era of Super-Sized Fleet Carriers, Set in Context