America's Undersea War on Shipping

Lieutenant Commander John S. Coye, skipper of the USS Silversides (SS-236), stared through his binoculars at the enemy convoy just past midnight on 29 December 1943. Rainsqualls peppered the night, making it the perfect conditions for a surface attack. The submarine’s radar revealed the convoy’s formation: two columns made up of three ships each protected by several small escorts. At ten knots, “Jack” Coye knew, the convoy would reach Palau by dawn. That left just five hours at best to intercept and attack. He had to work fast.

The 32-year-old officer would become one of America’s top World War II submarine captains, sinking 14 confirmed ships and earning three Navy Crosses. That tenacity was on display this night. In three hours he managed to destroy three ships, putting 7,192 tons of enemy shipping on the bottom. “Silversides had a busy night,” he wrote in his report, “firing 16 torpedoes.”¹

Coye was one of a small group of just 465 skippers who played a vital role in toppling imperial Japan. While much has been written about the Pacific’s dramatic naval battles— Coral Sea, Midway, Leyte Gulf—what is often overlooked is the dogged perseverance of and contribution made by American submariners, who week after week, month after month, hunted down and destroyed Japan’s naval and merchant ships. America’s submarine war boiled down to simple economics. Japan’s merchant ships served as the lifeblood of an empire that stretched across 20 million square miles and seven time zones. Merchant ships not only hauled the precious oil, iron ore, and rubber needed to fuel the nation’s larger war effort, but the toilet paper, tooth powder, and rice necessary to sustain fighting troops. American war planners recognized that Japan’s empire was tenuous at best; spread across thousands of miles of open water and sea lanes, its far-flung islands were difficult to reach and even harder to maintain.

Over the course of the war American submarines would help rescue 504 downed aviators, smuggle ammunition to embattled Corregidor, and protect amphibious landings, but the force’s principal mission was destruction. Its success resulted in part from important innovations in submarine design and strategy. Japan’s challenging geography and dependence on foreign resources only further aided the United States. More important, however, was the decision to target merchant ships.

President Woodrow Wilson had denounced this policy before Congress as immoral and a reason for war when U-boats carried out unrestricted submarine attacks 24 years earlier in the North Atlantic. But the attack on Pearl Harbor changed everything. America’s survival was at stake, prompting Chief of Naval Operations Admiral Harold Stark to dash off an eight-word order as fires still burned on Oahu: “Execute against Japan unrestricted air and submarine war.”²

The submarine war was fought one convoy—and even one ship—at a time. Torpedoed freighters vanished not only with experienced officers and crew but also with precious loads of bullets, bombs, and fuel—the last a tremendous loss considering a Japanese Zero in combat drank as much as 1,500 gallons of fuel a week and a single tank regiment could burn 2,000 gallons an hour.³ Each enemy cargo ship, troop transport, or tanker delivered to the bottom only slowed the enemy’s nimble war machine. “When Japan allied herself with Germany, not only did she join with the chief sponsor of unrestricted submarine warfare but her ships immediately became carriers of men, munitions and war supplies,” Vice Admiral Charles Lockwood, the architect of America’s submarine war against Japan, wrote after the conflict, “Therefore, no longer were there any Japanese merchantmen in the Pacific.”⁴

Evolution of Technology and Policy

America’s success in the submarine war resulted from important technological and policy advances made during the years following World War I. Engineers pulled apart and studied surrendered German submarines, which helped reveal the inferiority of American subs. U-boats boasted superb diesel engines that gave them greater cruising ranges along with double hulls that could better withstand depth-charge attacks. The boats sported better ventilation systems, air compressors, gyroscopes, and enhanced periscope optics as well as narrow penciled tops that cut down on wakes and made them harder for enemy lookouts to spot. More important, the boats could dive in just 30 seconds, far faster than American subs.

Engineers wrestled with how to overcome the inferiority of American designs at the same time policy makers debated the submarine’s role in future conflicts. Veteran officers challenged the traditional view that submarines operated best as part of larger fleet operations or as coastal defenders. Relegating the boats to guard American harbors and the Panama Canal failed to maximize a submarine’s unique capabilities. What other vessel could penetrate enemy harbors and sink ships?

Geographic and strategic realities factored into the debate. Even before the smoke had settled from World War I, American strategists saw the rise of Japan and the possibility of a future war in the Pacific. If America wanted to take the fight to foreign shores, it needed a submarine that could do so, one capable of traveling up to 12,000 miles and carrying enough torpedoes, fuel, and canned meat, vegetables, and coffee to last up to 90 days. Through this debate, the modern fleet boat, such as the Gato-class Silversides, was born.⁵

Commissioned just eight days after the attack on Pearl Harbor, the Silversides stretched 312 feet—roughly the length of a football field—but was just 27 feet wide. The submarine boasted nine watertight compartments, including two torpedo rooms capable of carrying 24 “fish.” Four Fairbanks Morse diesel engines propelled the Silversides on the surface at a maximum speed of 20.25 knots. When the klaxon sounded and the boat dove, enginemen shut down the diesels and switched to batteries. The submarine could submerge for up 48 hours at a two-knot crawl, before she needed to surface, fire up the engines, and recharge the batteries.⁶

There was little doubt the fleet boats were an upgrade from earlier submarines. That was evidenced by a letter from Lieutenant Gene Malone, who had served on three war patrols in the World War I–era submarine S-31 before landing as an officer on board the Silversides. “Gosh, this big boat life is wonderful. A shower we got, even,” Malone wrote his mother in November 1943. “We have staterooms, a wardroom and everything. Wonderful. Such luxury, for a change.”⁷

Despite the advances—and Malone’s endorsement—submarine life was austere. Sailors lived on top of one another in bunks stacked three high and just 18 inches apart. Others slept on cots strung between the 3,200-pound torpedoes. The men jokingly labeled the two bunks that dangled side-by-side from the forward torpedo room overhead the “bridal suite,” the close quarters usually occupied by a submarine’s African-American, Filipino, or Guamanian mess attendants.

Everything had to be designed around the concept of tight space and mission longevity. As a result, the entire boat served as a makeshift pantry. Sailors stashed crates of potatoes, cabbages, and carrots in the cool space beneath the deck in the forward torpedo room, while others lined cans of sugar, flour, and coffee along the narrow path that ran between the engines and the bulkhead. A plank laid across the cans allowed engineers to walk atop if needed. Others crammed food in the escape chamber and even filled one of the ship’s two showers with canned milk.⁸

Rather than clutter the galley with cumbersome bottles of soda, the Silversides carried 100 gallons of Coca-Cola syrup that could be mixed with fresh water and carbonated using miniature CO2 canisters. The same rationale applied to frozen meats; boneless was preferred. Cooks knew cabbage remained fresh longer than other vegetables while preserved fruits helped spark appetites, improve hydration, and battle constipation, a common ailment for submariners.⁹ Veterans learned to mix powdered milk with Avoset whipping cream to make the drink more palatable. The real pros even left a few eggshells out on the galley counters when serving powdered eggs, a subliminal message designed to trick the crew. “The flour would invariably wind up with weevils in it,” recalled Drum (SS-228) baker David Schmidt, who said the pests were too small to snare with a sifter. “If you were smart,” he added, “you put caraway seeds in it and made rye bread.”¹⁰

Entertainment likewise depended on creativity. Sailors passed the long hours over games of acey-deucey and cribbage. Others unwound in the crew’s mess and wardroom, listening to phonograph records of Bing Crosby, Glenn Miller, and Billie Holiday. Silversides engineer Lieutenant John Bienia, who served nine patrols, noted in a February 1944 letter to his wife that he managed to wear out five 1,000-record needles on the wardroom phonograph.¹¹ Sailors even had makeshift musical jam sessions, including one in the wardroom that featured a guitar, mouth organ, flute, and even a trombone, played by executive officer Lieutenant Commander Roy Davenport. To hit the low notes Davenport had to extend the slide out into the passageway, forcing sailors en route to the forward torpedo room to jump. Commander Creed Burlingame, the Silversides’ skipper for her first five patrols, even joined, playing a homemade bazooka. “There’s ugly talk going about the ship that we won’t have to shoot any torpedoes this trip, and that we can slay everyone with our music,” Bienia wrote in a letter. “Shucks, it seems that there are some people aboard ship who can’t appreciate the finer arts.”¹²

The war took no time off, not even for holidays. To remedy the blues in December 1942—while the Drum patrolled the waters around the Japanese island of Kyushu—executive officer Lieutenant Nick Nicholas recruited a few volunteers and decorated the crew’s mess and wardroom with red and green streamers, silver bells, and even imitation holly. “Christmas Day is here at last,” one sailor wrote on the boat’s unofficial calendar on 25 December. “We are fighting for the right to remember the past.” Cooks prepared a special noontime meal, which, according to the day’s printed menu, included a 29-pound turkey topped with “Yamamoto Gravy.” Speakers belted out “Jingle Bells” and “White Christmas” as Nicholas passed out token gifts to the crew that he had brought along for the occasion, including games, rattles, and whistles. “It was as if the war had taken a brief recess,” wrote Lieutenant (junior grade) Ira Dye Jr., the boat’s engineering officer. “An hour’s interlude of hometown America, just off the enemy’s coast.”¹³

The Enemy

Japan proved the perfect adversary for a submarine war. The archipelago made up of four major islands and several thousand smaller ones stretched almost 2,000 miles, from the icebound winter harbors of Hokkaido in the north to the azure waters and coral reefs of Okinawa in the south. Mountains crowded as much as 85 percent of Japan with towering ranges that traversed each of the major islands. The inhospitable terrain had played a crucial role in the evolution of Japan’s transportation systems. Mountains made railroad construction a challenge, and the necessary tunnels and bridges were expensive and vulnerable in wartime. The slow pace of rail construction had left Japan at the outbreak of the war with just two rail lines that ran the length of the main island of Honshu. With less than 6,000 miles of national roadways, most unpaved, the highway system proved equally primitive. One 77-mile trip across Honshu after the war would take American surveyors 12 hours.¹⁴

Japan’s dominant means of transportation instead revolved around the water—a vital maritime highway system that American strategists recognized proved an incredible liability in a submarine war. The concentration of shipyards, aircraft plants, and munitions factories on the central island of Honshu forced Japan to ship vital raw materials from its outer islands as well as internationally.

The nation’s inhospitable terrain caused greater strategic problems. Japan suffered a critical lack of farmable land, a fact made all the more severe given that the nation’s population had tripled to 73 million since it first opened its doors to the West. This growth made Japan the most densely populated nation per arable acre in the world, with 2,774 people crowded per acre compared to just 230 in the United States. Fishermen sailed as far as the Panama Canal and Alaska to feed the population. Outside of a handful of industries, such as fish oil and silk, Japan had almost no material self-sufficiency; it was forced to import even rice.¹⁵

These deficiencies were more acute in the demand for war materials, from the bauxite necessary to manufacture fighters down to the rubber needed to make tires and the cotton to sew uniforms. Nowhere was that demand more critical than with oil, the lifeblood of any modern military. At the outbreak of the war, Japan could produce just two million barrels of oil a year, a figure that equated 0.1 percent of the world’s output. The United States, in contrast—the world’s dominant producer—could deliver 700 times that amount. Until a few months before the war, the United States had supplied as much as 80 percent of Japan’s oil. Investigators later concluded that American oil likely powered the carriers, bombers, and fighters that attacked Pearl Harbor.¹⁶ Japan’s hunger for food and raw materials had put it on the path to war with the ultimate goal the capture of the oil-rich Dutch East Indies (present-day Indonesia).

Targeting Freighters, Tankers, Transports

Despite Japan’s geographic and raw-material challenges, the United States, handicapped by a lack of submarines, still struggled at the outbreak of the conflict. Of the 111 boats America had at the time the Japanese attacked Pearl Harbor, only 51 were assigned to the Pacific—and just 39 of those were modern fleet boats, like the Silversides and Drum. The rest were leftovers from around the time of World War I, boats largely incapable of making long war patrols to the enemy’s homeland. Given the great distances and the need for refits and overhauls, only about one-third of submarines could be on station and patrolling eight million square miles of ocean—an area more than twice the size of Europe—at any given time.¹⁷

To manage this seemingly impossible task, the Navy created dozens of numbered patrol areas that covered Japan’s home islands as well as strategic locations such as the Marianas, the Dutch East Indies, and Formosa (present-day Taiwan). In creating the areas, war planners looked not just for enemy naval bases, but for vital shipping centers. Other patrol areas covered important sea lanes and zones where multiple shipping routes converged, places war planners knew to expect maritime traffic.

The Navy then assigned submarines headed out on patrol a specific area in which to hunt. In early 1943, analysts broke what many dubbed the “maru code,” the Japanese cryptosystem used to route merchant ships through empire waters. The daily noon position reports of each convoy combined with the 0800 and 2000 reports of individual skippers allowed American analysts to plot Japan’s freighters, tankers, and transports in real time. Gone was guesswork and luck; all a submarine skipper had to do was intercept a convoy on its scheduled course, shadow the ships, and set up the perfect attack.¹⁸

The Silversides was among the initial boats to benefit from this new intelligence. On his fourth patrol off the Caroline Islands, Lieutenant Commander Burlingame received one of his first messages based on the decryptions, alerting him that the 10,023-ton tanker Toei Maru would reach Truk at 0010 on 18 January. Burlingame picked up the target ahead of schedule and fired four stern tubes at 0255. The skipper watched as multiple fish crashed into the tanker. “Tremendous explosion and pillar of black smoke 200 feet high,” Burlingame wrote in his report, “flame and sparks at its base and out stack.”

Intelligence alerted the skipper just four days later of a four-ship convoy that carried more than 4,000 Japanese soldiers and horses. Burlingame picked up the vessels on 20 January, firing six torpedoes that hit the passenger cargo ship Sonedono Maru, freighter Surabaya Maru, and freighter Meiu Maru. He put 17,775 tons of enemy ships on the bottom and killed more than 800 Japanese servicemen. “The sound of ships breaking up,” he wrote in his patrol report, “was clearly heard for the next half hour.”¹⁹

American Challenges

America wasn’t without its struggles. The largest and most controversial centered on the Navy’s faulty torpedoes. From the opening shots of the war, skippers griped that the complex weapons—made from 1,325 parts and with a price tag of more than $10,000 each—often malfunctioned.²⁰ Gunnery officer Lieutenant Maurice “Mike” Rindskopf, who would rise at the age of 26 to become the youngest fleet-boat skipper in the Pacific, charted the failures during the Drum’s third patrol when 9 out of 23 torpedoes failed to hit. He presented his analysis to the skipper, Lieutenant Commander Robert Rice, who included it in his report. “No one likes to blame his tools,” Rice wrote. “I cannot but feel that we accomplished only half of what we earned, and even a smaller fraction of what we were capable of doing.”²¹

Rather than investigate the problem, the Bureau of Ordnance blamed the skippers as bad shots. Admiral Lockwood, however, refused to shrug off the complaints of his men. Tests off of Australia, where the Skipjack (SS-184) fired into a fishing net, confirmed that the torpedoes ran on average 11 feet too deep. Even then, problems with faulty fish would stretch on for much of the first two years of the war, robbing skippers of the chance to put valuable targets on the bottom and slowing America’s effort to cripple Japan’s economy. According to submarine historian Clay Blair Jr., “The torpedo scandal of the U.S. submarine force in World War II was one of the worst in the history of any kind of warfare.”²²

Another challenge America faced early in the war was a lack of experienced skippers. Though the United States had built the perfect offensive weapon, many boat captains who had trained during peacetime proved too timid in combat and failed to maximize the submarines’ inherent strengths. That changed thanks to the work of pioneering captains such as Commander Dudley Morton of the Wahoo (SS-238). Morton’s prominent mouth and ear-to-ear grin earned him the nickname “Mushmouth”—later shortened to just “Mush”—after the character in the popular Moon Mullins comic strip. The skipper fueled the name by showing off his trick of stuffing four golf balls in his mouth at once.

Morton approached submarine warfare like wrestling, which he had excelled at as a midshipman at the U.S. Naval Academy. He believed that to sink ships you had to get in close and grapple with your opponent. Submarines were better suited to run on the surface to cover greater distances. Morton assigned more lookouts to help spot targets, and during an attack he would return to a target again and again until he put it on the bottom.

Morton’s aggressive new tactics worked. During the Wahoo’s third patrol, he claimed to sink a staggering five ships, though a postwar review of Japanese records could confirm only three kills. He was the first skipper to claim to sink an entire convoy. On the Wahoo’s fourth patrol, Morton reported that he had destroyed eight ships, a figure that postwar review of Japanese ships would actually bump up to nine, setting the record at the time for the most ships sunk on a single patrol.

Morton’s aggressiveness, however, would ultimately cost him his life. Caught in shallow waters off the Japanese home island of Hokkaido, the Wahoo was destroyed by the enemy in October 1943, a loss that shocked the submarine community. “It just didn’t seem possible that Morton and his fighting crew could be lost,” Lockwood later wrote. “I’d never have believed the Japs could be smart enough to get him.”²³

In his short time as skipper, Morton had demonstrated the awesome power of America’s new submarine. There is no better evidence of Morton’s success and legacy than in the performance of his protégé, Commander Richard “Dick” O’Kane, who had served as the Wahoo’s executive officer before the Navy promoted him to skipper of the Tang (SS-306). Over the course of nine months in 1944, O’Kane sank a confirmed 24 ships—an average of one destroyed for every ten days he was on patrol, and he would be credited with sinking more ships than any other skipper of the war. His destruction of ten ships during the Tang’s third patrol earned O’Kane the war’s record of the most ships sunk on any one mission. On a patrol off Truk during American air strikes against the atoll that spring, he earned another distinction when he helped rescue 22 downed aviators, a story that landed on the pages of Life magazine.

But O’Kane’s fortune ran out in October 1944 off the coast of Formosa. He fired his final torpedo of the patrol at a crippled ship only to watch in horror as the malfunctioning weapon circled back and hit the Tang. The skipper and eight other survivors would spend the next ten months in Japanese prisoner-of-war camps. He emerged at the war’s end weighing less than a hundred pounds. President Harry S. Truman would later present O’Kane the Medal of Honor, one of seven sub captains to receive the nation’s highest award for heroism. “He was just skin and bones. His arms and legs looked no bigger than an ordinary man’s wrists,” Lockwood recalled. “His eyes were yellow with jaundice, but that is the only yellow in O’Kane’s makeup.”²⁴

The Campaign’s Success

Engineers, welders, and electricians at shipyards from Maine and Connecticut to Wisconsin and California hammered out new submarines week after week, achieving a peak production of ten new boats a month in 1944. When the Navy broadcast the cease-fire order at the war’s end, 182 boats were on duty. All told, 288 served in the war. The submarine service throughout remained small, never exceeding 50,000 officers and enlisted men, or just 1.6 percent of the Navy. Only 16,000 of those served at sea.²⁵ Over the course of the conflict, American submarines attacked 4,112 merchant ships, firing 14,748 torpedoes. A postwar comparison of American and Japanese records revealed that U.S. submarines sank 1,113 of those ships, with a total tonnage of 4,779,902. The undersea service destroyed another 201 warships, including a battleship, 8 carriers, and 11 cruisers. Authorities listed dozens of other merchant and warship losses as probable victims of American submarines. That success, however, came at a steep price. The United States lost 52 submarines—almost one out of every five. With those went the souls of 374 officers and 3,131 enlisted men.²⁶

Japan’s dependence on shipping had proven the Achilles’ heel of the nation’s war machine. This critical vulnerability had allowed America to ravage an empire that at its height had dominated one-tenth of the world. With oil imports halted, Japan had no choice but to park many of its carriers and battleships, relegating them to antiaircraft duty. Military trucks were left to putter around bases by burning charcoal. Engineers battled gasoline shortages with substitutes of ethanol, methanol, and acetone, while others converted confiscated rice, sweet potatoes, and sugar to alcohol. Even precious bottles of sake vanished from store shelves. The Japanese grew so desperate that by 1945 workers built some 40,000 small distilleries in an effort to harvest oil from pine roots.²⁷

To keep fighters in the air, Japan slashed gasoline quality from 92 octane to 87 as engineers modified engines to burn alcohol. Pilots had once received 100 hours of basic training but by the final months of the war received as little as 30 and no navigation instruction. Fliers would simply follow one another into combat as mission losses soared as high as 70 percent.²⁸ Fuel scarcity even forced leaders to resort to kamikaze attacks. “There was no prospect for victory in the air by the employment of orthodox methods,” Lieutenant Colonel Naomichi Jin, an air army operations staff officer, told interrogators after the war. “Suicide attack was the only sure and reliable attack by airmen whose training had been limited because of the shortage of fuel.”²⁹

The civilian population was forced to battle food shortages, a thriving black market, and widespread malnutrition. The Japanese tried to make butter from silkworms and even ate acorns, chafe, and sawdust; the government went so far as to advertise that sawdust from red pine was the most nutritious.³⁰

By the waning months of the war, the nation’s social fabric began to fray. The hungry population could take it no more. American submarines had strangled Japan. “The war against shipping,” concluded the U.S. Strategic Bombing Survey, “was perhaps the most decisive single factor in the collapse of the Japanese economy and the logistic support of the Japanese military and naval power.”³¹