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Robert Lee Shaw was asleep when mayhem struck. It was near midnight, July 25, 1942, and Shaw was serving with an American guard detachment aboard the Dutch steamer Tjinegara. The ship had been home ported in Batavia—now Jakarta—until the Netherlands East Indies fell to Japanese invaders. Now the freighter’s owners, the Java-China-Japan Line, were leasing the 9,200-ton vessel to the U.S. Army as an animal transport. Tjinegara was bound from Australia to the French colonial port of Nouméa, New Caledonia, with a load of 477 horses, a road grader, and 2,000 cases of beer. The Southern Cross dominated the night sky. Tjinegara would not see the dawn.

Watching through his periscope, Lieutenant Commander Katsuji Watanabe of the Imperial Japanese Navy submarine I-169 was determined to sink the enemy vessel. Eight months earlier, Watanabe and I-169 had been waiting off Pearl Harbor, prepared to recover crews of the midget submarines assigned to attack the U.S. Pacific Fleet. Watanabe had seen the flames towering in the harbor, but none of the midget sub crews reached his sub-marine. Lingering too long, the I-169 had been depth-charged and caught in antisubmarine nets and damaged, and had failed in an attack on a cargo vessel near Hawaii. A few months later, Watanabe and I-169 had been posted on the sea-lane connecting Hawaii to Australia, but found nothing. Now he was scouting for targets off New Caledonia and the New Hebrides, with the division commander aboard looking over his shoulder. Watanabe fired torpedoes. One hit.

Startled by the explosion, Seaman Shaw bounced out of bed and ran toward Tjinegara’s bow. He smelled gunpowder and heard the abandon ship order. Shaw had left $5 at his bunk and his lifeboat station lay below the bridge, so he went back for his money and his suitcase. On the way he saw a gaping hole in the hull. Tjinegara’s captain was ahead of him into the lifeboat. They rowed to the freighter’s opposite side, where they found one of the horses had broken loose and was thrashing in the water. The men feared the frightened animal might try to climb into their boat, but they refrained from shooting it; blood would attract sharks. Just then the captain glimpsed a periscope. The attacking submarine had also circled the stricken ship, and fired another torpedo.

The Dutch freighter was done for. Shaw survived because an American destroyer rescued him and the captain the next night. By then the Japanese submarine was long gone.

Captain Watanabe’s mission was a reflection of the Imperial Navy’s keen interest in the South Pacific, where the Japanese had taken over the Solomon Islands and were building an airfield on Guadalcanal. The Allies were interested, too: by August 15, when I-169 reached the Japanese base at Truk, American forces had been on Guadalcanal for a week.

To stay alive, Allied invaders needed seaborne supply from their nearest bases: the New Hebrides island of Espíritu Santo, about 400 miles southeast of Guadalcanal, and Nouméa, another 450 miles south. A motley fleet ranging from fast destroyer-transports to cargo vessels—even ocean tugs—was laboring to support the 10,000 American troops on and around Guadalcanal. From Espíritu, a fast ship could reach the island in a day and a half. A merchant vessel on the Nouméa-Guadalcanal run needed almost four days—and a naval escort.

To beat back or blunt the first Allied offensive in the Pacific, Japan needed to cut that lifeline. While Japanese battleships, cruisers, carriers, and other vessels fought on the surface to hold the Solomons, the Imperial Navy tried to starve Guadalcanal with airpower and submarines.

The resulting aerial and surface battles are famous. But far less is known about the underwater offensive the Japanese waged in the Guadalcanal supply corridor that became known as Torpedo Junction, and undeservedly so. Careful analysis shows Japanese submariners to have been as effective there as the empire’s surface navy—that is, until Japan’s submarine campaign foundered on the empire’s rigid naval doctrine.

As soon as U.S. Marines landed on Guadalcanal, Japanese admirals at Rabaul, the empire’s main base in the Solomons, ordered submarines to those waters—a move that effectively suspended the underwater war on merchant ships like the Tjinegara off Australia until late January 1943.

Based at Rabaul, 570 miles away, and commanded from there by Rear Admiral Setsuzo Yoshitome, the boats of Submarine Squadron 7 were to operate in the immediate vicinity of Guadalcanal. Submarine Squadron 3, which had been hunting freighters off Australia under Rear Admiral Chimaki Kono, would come from Truk, 2,000 miles from Nouméa and 1,140 from Guadalcanal. In Japan, Rear Admiral Shigeaki Yamazaki was poised to take Submarine Squadron 1 to the Indian Ocean; instead, Yamazaki was ordered south. He boarded I-9, and on August 15 sailed with four more I-boats. Japanese Combined Fleet commander Admiral Isoroku Yamamoto assigned Vice Admiral Nobutake Kondo-, his advance force leader, as the overall submarine commander.

Kono, Yamazaki, and Kondo- each had strengths, though only Yamazaki was a full-fledged underwater man. Kondo-, 56, was academically brilliant. At the top of his class in the Imperial Japanese Naval Academy, he taught at and later headed the Imperial Navy’s war college. But he knew little about subs. Yamazaki, 49, was a torpedo specialist with nearly 30 years of navy service. Thin-faced, with a prominent lower lip, Yamazaki was leading a division of subs as early as 1934, and by 1940 was a squadron commander. He had had a major role in submarine operations around Pearl Harbor, and later took his boats to Alaska’s Aleutian Islands. Kono, 50, was a radio expert who had a great deal of time as a staff officer—including assignments with the Combined Fleet and the Navy Ministry—and had captained battleships and cruisers. But before taking command of an I-boat squadron he had never served aboard a submarine.

Kondo- designated a corridor between San Cristobal in the Solomons and Ndeni in the Santa Cruz Islands, effectively creating Torpedo Junction. He detailed Yamazaki’s six subs and Kono’s Squadron 3 to patrol a line within that corridor, and would issue instructions as the battle evolved. In essence, Kondo- treated subs like surface ships. But submarines on the surface sat too low to be practical for scouting—and were even less useful for that purpose at periscope depth. Subs were more effective stationed at choke points where enemy essels had to pass.

By August 23, Yamazaki and his I-boats lay east of Malaita Island, by the lower Solomons, about 250 miles from their destination. That day, aircraft from the American carrier Enterprise caught Lieutenant Commander Takakazu Kinashi’s I-19 on the surface, forcing the sub to crash-dive to escape bombs. The next day an Enterprise plane unsuccessfully pursued Lieutenant Commander Hakue Harada’s I-17. By the next night, August 24, the subs reached their destination. The six boats set up a blockade line roughly 150 miles wide.

Early on August 25, Commander Nobuo Ishikawa in I-15 saw an enemy fleet, and identified the carrier Enterprise and the battleship North Carolina. He tried unsuccessfully to signal nearby I-17, sending Morse code by hydrophone. Haphazard attacks by Allied destroyers kept I-15 submerged, but eventually Ishikawa was able to surface and pursue the carrier. Yamazaki ordered I-17 to assist, but even working together the crews lost contact in the predawn darkness.

Also on August 25, in an attempt to maneuver the subs to catch the Allied fleet, the Japanese command ordered its subs to a line bearing southwest from Ndeni. At midday, a destroyer in the U.S. carrier Saratoga’s screen spotted the I-9. Three escorts joined together for five hours of depth charging. When the attackers finally saw bubbles and an oil slick, they moved on.

The Americans had fallen for a classic ruse. The captain of Yamazaki’s command vessel, Lieutenant Commander Akiyoshi Fujii, dumped fuel and belched air from a torpedo tube, faking the I-9’s demise and slipping away. Meanwhile, aboard the I-19 Kinashi had sighted two enemy ships but could not close. More subs, working as a group west and south of Guadalcanal, reached position south of the Indispensable Reefs, a series of atolls at the western edge of the corridor that Japanese subs often used to refuel long-range scout bombers.

The Japanese lacked the submarine strength needed to saturate Torpedo Junction and trap American vessels. On August 26, Kinashi’s hydrophones detected a surface force—which happened to include the American carrier Wasp—but the Allied vessels easily outran his submerged vessel. On August 28 the I-15 spotted another American carrier, which several subs pursued without success. Such results made the Battle of the Eastern Solomons a disappointment for the undersea force.

Yamazaki, tired and perhaps dispirited from his trial by depth charge five days earlier, arrived at Truk on August 30 and tied up I-9 for repair. One by one, other I-boats straggled in. A few days later, accompanied by the Sixth Fleet chief of staff, Rear Admiral Hisashi Mito, Yamazaki went to the Combined Fleet flagship, the superbattleship Yamato.

The Sixth Fleet had been Japan’s top submarine command since 1940, and Mito, like Yamazaki, was a true submariner. Yamazaki had commanded his first boat in 1920; the 50-year-old Mito had received his first sub command in 1923. Aboard Yamato the men met with Combined Fleet chief of staff Rear Admiral Matome Ugaki to discuss the subs’ recent experience.

Yamazaki said the Allies’ precautionary measures had been good and their sound detection excellent—analysis that Mito seconded. Ugaki drew the correct conclusion: “If a chase is difficult and an underwater movement dangerous, the only thing we can do is lie in wait with many submarines.”

These were not fresh insights. The I-boats’ meager results reflected the difficulties inherent in this kind of operation. A spring 1941 exercise by Squadron 2 that ranged from Japanese waters to Micronesia had shown the subs to be too slow for pursuit and too few to monitor broad ocean expanses. To avoid detection, subs had to remain distant from enemy harbors, which allowed foes to sortie without warning. Even when stationed right off enemy bases, subs had trouble engaging high-speed surface fleets. At Torpedo Junction, Allied task forces sped across the submarine patrol line, offering the undersea boats scant opportunity to maneuver. Placing subs under a surface officer like Kondo- brought other problems. Assumptions were critical in this hide-and-seek contest, and commanders unfamiliar with underwater combat tended to make the wrong ones.

The Imperial Navy’s fleet-centered operational concept dictated that subs remain in a line rather than patrol an area. As seen at Midway and now at the Eastern Solomons, this stiffness negated many of the advantages of group operations—but at least the repeated cruises familiarized Japanese sub skippers with Torpedo Junction and the behavior of the Allied forces crossing it. And while the Allies evaded the I-boats at the Eastern Solomons, Torpedo Junction featured a steady stream of American interlopers trying to outsmart their foes, which constantly presented the Japanese with fresh opportunities made challenging by the Imperial Navy’s perceived wisdom.

For example, on the night of August 24, the I-boat group occupied exactly the waters from which the American carriers had fought that day—arriving roughly 12 hours late. When Yamazaki’s subs reached their August 25 positions, they were behind every American except the Wasp, which had gone to refuel and then steered north. By then, most enemy targets were headed home, not obliged to maintain position to do battle.

The subs had done as ordered and hewed to Imperial Navy doctrine, which was both visionary and constraining. Japan intended its I-boats to act in conjunction with the navy’s advance force, whittling down foes before decisive battles. The navy was ahead of its American and German counterparts, and in the 1930s had developed the group assault tactics for use against warships that Germany would make famous with its convoy-hunting wolf packs. Japan had even built specialized command boats to lead formations into battle. Its regular subs had range and endurance—16,000 miles and 90 days, compared with the 11,000 miles and 75 days of America’s mainstay Gato-class subs. Japan had also developed a submarine-based floatplane along with a number of subs with facilities for storing, launching, and retrieving them, which enabled subs to scout remotely.

But Japan’s sub command had serious flaws. While Sixth Fleet staff chief Mito was a true submariner, his boss, Vice Admiral Teruhisa Komatsu, was not. Komatsu, 54, once led a sub squadron, but the only warship he had skippered was a cruiser and he had never driven an undersea boat. Komatsu, who had also taught at the naval academy and the navy war college, was drafted into the submarine command in early 1942 when the previous Sixth Fleet boss was wounded. Now Komatsu was being called upon to oversee the subs at and around Guadalcanal.

On the night of August 31, Lieutenant Commander Minoru Yokota’s I-26 was running on the surface northwest of Espíritu Santo, charging its batteries, when a lookout spotted lights. Diving cost Yokota contact, but hours later he regained it—and discovered that the lights belonged to the Saratoga’s task force. At periscope depth I-26 could not keep up, but a zigzag put the carrier right in front of the sub. A torpedo broached Saratoga’s aftermost fire room and compromised its electrical circuits. Destroyers responded, but I-26 disappeared.

The temporary loss of the Saratoga sapped Allied strength and stoked concern about submarines. Fearing the Japanese might penetrate their harbors, Allied commanders ordered Espíritu’s minefields augmented. A key passageway called Segond Channel was liberally seeded. (In August an American destroyer had blundered into the field and been sunk; the same fate awaited the transport President Coolidge in October.) Off Nouméa, the Allies mounted a 24-destroyer watch at Amedee Light, where the barrier reef opened to the sea. When a fleet or convoy departed, escort vessels first cleared the approaches. And Allied ships routinely went to battle stations at sunset and dawn, when the light favored subs but surface sailors might be tired after a long day or not quite ready for a new one. The rest of the time the surface vessels generally remained at the ready.

By early September the Japanese had eight subs cruising Torpedo Junction and several more off Guadalcanal. On September 6, off Espíritu, I-11 got inside the carrier Hornet’s screen. It might have done some damage but for an alert patrol plane crew. The airmen dropped bombs whose explosion diverted I-11’s torpedoes. The counterattack was fierce. Aircraft damaged I-11 so badly that the sub had to leave Torpedo Junction on the surface, barely making Truk. Since I-11 was Kono’s command ship, his role in Squadron 3 was compromised. So on September 8, the day after Yamamoto ordered Guadalcanal blockaded, the Sixth Fleet transferred control of all subs in Torpedo Junction to Yamazaki. Kondo- followed with particular instructions for the blockade.

On September 13, a Japanese flying boat sighted another American carrier, prompting Yamazaki to order the patrol line to shift south 100 miles. On September 15, I-19 skipper Kinashi spotted Allied warships. The enemy sped away but, as in the Saratoga incident, zigzagged right to I-19. Kinashi launched a full spread of six torpedoes, sinking the carrier Wasp and the destroyer O’Brien, and damaging the battleship North Carolina—the most successful Japanese sub attack of the war.

On the blockade, submarine patrol strength remained problematic. By September 23, a dozen I-boats were on station, with seven in port for service. On September 29, I-4 damaged the 7,400-ton merchant ship Alhena on its return from Guadalcanal.

In October, illness forced the warhorse Yamazaki to leave Truk; Mito replaced him as head of Squadron 1. In one respect the change reduced difficulties: with Yamazaki gone, Kono, the other submarine squadron commander, became the key man. Kono still lacked sub savvy, but his deep radio expertise made him well equipped to handle the chronic radio problems that underwater crews experienced in the tropics.

Meanwhile, the Japanese Combined Fleet was readying a major operation to reinforce Guadalcanal, overwhelm the Americans there, and cripple any fleet the Allies sent to save them. Subs would have a key role. In early October, Komatsu took direct control of four I-boats to put floatplane scouts over key Allied bases. Nine other subs were undergoing upkeep at Truk and Rabaul. Only five subs were patrolling Torpedo Junction; one, I-22, was apparently lost on October 6 to an American PBY’s bombs. At mid-month, when the Japanese surface fleet went on the move, the blockade force surged. Kono suddenly put 16 I-boats, divided into two forces, into Torpedo Junction waters, continually adjusting their patrol lines.

The payoff came October 20. Aboard the I-176, Lieutenant Commander Yahachi Tanabe thought he spied a battleship, but what he torpedoed amidships was the heavy cruiser Chester, which limped back to Espíritu with 11 dead and 12 wounded.

The carrier battle of the Santa Cruz Islands began on October 25, northwest of Guadalcanal. As Allied vessels withdrew, I-boats gave chase, with the usual detection and pursuit problems. Lieutenant Commander Kanji Matsumura’s I-21 fired at the American battleship Washington, but his torpedo exploded in the ship’s wake. In the melee, the battleship South Dakota and the destroyer Mahan collided, badly damaging each other. Except for the Chester, Japanese subs drew scant blood.

Even so, the running scorecard for Torpedo Junction was clear: the Imperial Navy had lost I-22, and other subs had suffered damage. But thanks to the Japanese submariners the Allies had lost a carrier and a destroyer, and had a carrier, a battleship, and a heavy cruiser damaged—not counting the vessels damaged in minefield accidents and scrambles to avoid I-boats. And since the Enterprise, badly damaged by Japanese aircraft at Santa Cruz, had withdrawn to Nouméa, the Allies in the South Pacific had no combat-ready carrier. A significant portion of American losses was thus the work, direct or indirect, of Japanese subs.

After the Battle of Santa Cruz ended on October 27, the Japanese sub commanders wasted no time on the next move: a special mission conceived by Mito against Espíritu Santo and Nouméa, codenamed Button and Poppy. As with the creation of Komatsu’s special reconnaissance force before Santa Cruz, Mito’s plan was shaped by the Japanese thinking strategically rather than woodenly following procedure.

The raid was sure to be non-standard: its leader was Captain Hankyu Sasaki, and if the Imperial Navy had a commando submariner, he was it. Sasaki, 46, had led the midget subs at Pearl Harbor, and a May 1942 midget raid on the port at Sydney, Australia. Well-connected—he and Ugaki were naval academy classmates—Sasaki had helmed subs since 1920, and had led Submarine Division 3 since 1939. On October 28, Mito created the independent E Force under Sasaki and sent it to Nouméa.

The timing was ideal. September through October is Nouméa’s dry season, averaging only nine rainy days a month with temperatures in the 70s. November is slightly warmer and wetter, but with almost identical sunshine—optimal conditions for deploying floatplanes and scout submarines off ports. The Japanese had thought of hitting the Allied bases—they even discussed an October raid on Nouméa using naval infantry inserted by submarine—but the intended boat was diverted and preparations for Santa Cruz occupied most subs. The three-vessel E Force mission seemed more practical.

Sasaki sailed aboard I-21, commanded by Matsumura, a veteran of a patrol off Nouméa and among the top-scoring sub captains. The second boat, I-9, was captained by Fujii, the lieutenant commander who had evaded American destroyers with his oil-and-air trick. A scouting maven, Fujii had launched floatplanes against Pearl Harbor and in the Aleutians. He and Matsumura were both from one of Kono’s forces. The trio’s third sub, Kinashi’s I-19, came from Komatsu’s recon force. Kinashi had killed the Wasp, and E Force was after the Enterprise.

Fujii began the mission by reconnoitering Nouméa on October 31, the day after the Enterprise anchored there. An outside I-boat, I-8, did likewise at Espíritu two days later. At dawn on November 4, Fujii sent his floatplane over Nouméa. The pilot reported one carrier, several cruisers, and other ships.

Sasaki was having the problems near Allied bases that the spring 1941 exercises had exposed. Under ordinary circumstances he would not have dared let subs get too close to an enemy harbor, but this situation was special. Perhaps Sasaki intended to raid directly into the harbors, as U-boat skipper Günther Prien famously did at Scapa Flow, Britain’s main naval base, in 1939. However, there is no record and Sasaki, Fujii, and Kinashi did not live to write postwar memoirs. Sasaki’s scouting pattern suggests he was angling for some kind of attack on the harbor at Nouméa, but could not get past the destroyer patrols at Amedee Light.

In any event the subs held off, while inside Nouméa’s harbor American sailors swarmed the Enterprise around the clock, along with every engineer and repair specialist the U.S. Navy could find. Men from the repair ship Vulcan and Seabees labored alongside the carrier’s damage control people. Assayers said repairs would take three weeks; the work was done in 11 days. Enterprise crewmen were recalled from liberty—pulled out of downtown bars where a can of beer was 15 cents and whiskey was a quarter a slug.

As E Force circled, Japan’s Combined Fleet was readying a fresh naval offensive against Guadalcanal that demanded more floatplane reconnaissance. However, the floatplane on Komatsu’s I-7 was too damaged to scout Espíritu Santo. The admirals ordered Sasaki to detach I-9 from E Force so its plane could replace I-7?’s. That took Sasaki’s best scout boat away from the Enterprise’s lair. Off Espíritu, I-9 would be too distant to play a role at Nouméa.

The climax came on November 9. Enterprise, refurbished enough to get under way, left Nouméa with two battleships for company and repair crews still toiling on board. From both Nouméa and Espíritu, cruisers and destroyers departed to convoy half a dozen transports to Guadalcanal.

The Japanese learned their quarry had exited that day, when I-21’s floatplane overflew Nouméa. At sunset on November 11, Fujii’s airmen reconnoitered Espíritu, reporting that harbor empty as well. The subs had been too far from the enemy bases to detect ship movements or attack Allied vessels. Nor had it dawned on the submariners to attack the U.S. escort carrier Kitty Hawk, then nearing Espíritu with a load of planes for Guadalcanal.

After Enterprise fled, the Japanese got a small consolation prize. Off Nouméa, I-21 spied Liberty ship Edgar Allen Poe inbound. Matsumura lined up. His torpedo ran true. The Poe’s crew abandoned ship. Matsumura wanted to finish the transport with his cannon, but Poe’s guards had a deck gun. The I-boat dived.

Escorts arriving to rescue Poe’s crew found the ship afloat, decks buckled but bulkheads intact. After repairs at Nouméa, the Poe became a sort of ocean-going barge until Japan’s surrender, dispensing supplies from a towline. I-21 was credited erroneously for sinking it, an ironic coda to an ambitious raid.

The denouement at Torpedo Junction came quickly. With Japanese surface ships bearing down on Guadalcanal, Sasaki was ordered to patrol. But his and other I-boats from Truk saw no game. After its scout mission at Espíritu Santo, I-9 received orders to harbor at Shortland Island, a Japanese base northwest of Guadalcanal. The I-19 followed. Sasaki remained at sea with I-21 until he returned to Truk. Midget subs at Guadalcanal succeeded only in damaging one Allied ship. Kondo-’s advance force lost the epic November 12–15 surface fight known as the Naval Battle of Guadalcanal, but I-26 did pick off the crippled light cruiser Juneau, costing the Americans 687 men, including the five Sullivan brothers.

After the big fight, the Imperial Navy suddenly demoted I-boats to supply duty—a step with no precedent, taken in desperation to succor starving Japanese soldiers on Guadalcanal. Subs occasionally hauled supplies, but the November order made that their primary task. Submarine skippers protested. Komatsu overrode all objections, and the supply order effectively ended the Torpedo Junction blockade. Pulling I-boats from combat patrol amounted to virtual attrition—Japanese warships taken out of play without direct Allied action.

From Shortland, I-19 and I-9 began supplying Guadalcanal. Soon I-boats were provisioning New Guinea. In time, Imperial General Headquarters formally assigned submarines and destroyers to supply Japan’s endangered garrisons.

After November 1942 the Japanese occasionally patrolled Torpedo Junction, sinking transports as late as summer 1943. But the sub squadrons’ heyday was done. The Guadalcanal blockade had failed, the war in the Pacific had passed Torpedo Junction by, and despite a respectable record against American warships, Japan’s submarines had—by its navy’s own hand—been scuttled to the status of underwater delivery wagons.