The Torpedo Crisis and Strategic Shift

In the early stages of America’s submarine campaign across the Pacific, an unexpected crisis emerged that had nothing to do with enemy action. By mid-1944, Pearl Harbor’s torpedo stocks had swollen to unprecedented levels – 200 electric Mark 18 torpedoes and 1,005 steam-powered Mark 14/23 torpedoes filled storage areas to overflowing. This abundance marked a dramatic turnaround from earlier desperate shortages that had left submarine commanders frustrated.

The logistical situation reached such proportions that torpedo shipping crates piled up outside base facilities, prompting recommendations to scale back production. This surplus reflected both improved American industrial output and the changing nature of Pacific naval warfare. As Allied surface fleets and amphibious forces advanced, the hunting grounds for submarines gradually contracted, reducing torpedo consumption from its peak of about 350 monthly.

Technological Arms Race Beneath the Waves

1944 witnessed a quiet revolution in undersea warfare technology. The “Sea Fox” submarine received the first integrated radar-equipped night periscope, though deployment to Pearl Harbor units lagged. Two new ultra-shortwave radar systems promised improved air and surface detection, but production delays persisted due to higher priorities given to amphibious forces’ electronic equipment.

A disturbing pattern emerged regarding older SD radar systems. Multiple American submarines had been sunk after Japanese aircraft apparently tracked their radar emissions. This vulnerability forced captains to use the systems only intermittently, creating an urgent need for safer detection technology. Meanwhile, captured German technology and British innovations like the XE-class midget submarines prompted debates about adopting similar specialized vessels, though concerns about diverting resources from proven fleet submarines ultimately prevailed.

The “Convoy College” Killing Grounds

The South China Sea’s northern sector, nicknamed “Convoy College” by American submariners, became a particularly productive hunting ground. August 17, 1944, typified the intense action when the USS Redfish spotted a southbound convoy including the Japanese escort carrier Taiyo. This marked Japan’s adoption of Atlantic-style convoy tactics, though with questionable effectiveness.

The subsequent engagement demonstrated evolving American wolfpack tactics. The USS Rasher, under Commander Hank Munson, executed textbook attacks – first striking a large tanker carrying aviation fuel (creating a spectacular 1,000-foot fireball), then slipping undetected through the chaotic Japanese counterattack to sink multiple ships with well-placed torpedo spreads. In one deadly night, Japan lost the 20,000-ton Taiyo plus 38,547 tons of merchant shipping.

Special Operations and Beach Reconnaissance

As amphibious operations expanded, submarines took on unconventional roles. The USS Burrfish conducted perilous photographic reconnaissance of Peleliu and Yap, while specially trained naval teams made nighttime rubber boat landings to gather vital tidal and beach data – intelligence critically lacking during the bloody Tarawa landing. These missions carried extreme risk; on Yap, three of four scouts were captured, compromising the operation.

The value of such intelligence was immense. Detailed charts of reef passages and water depths determined whether Higgins boats, amphibious trucks, or Alligator tanks could be deployed – knowledge that meant the difference between success and another Tarawa-style bloodbath.

The Human Cost: Losses and Rescues

September 1944 brought both triumph and tragedy. American submarines achieved record sinkings – over 400,000 tons of Japanese shipping by some estimates, representing two-thirds of Japan’s merchant fleet. But losses mounted too, with 28 submarines lost to enemy action and six to accidents.

The month’s most poignant episode involved the sinking of the Rakuyo Maru, unknowingly carrying 1,350 British and Australian POWs from Singapore. After American torpedoes struck, Japanese crews abandoned ship, leaving prisoners to fend for themselves. Four days later, the USS Sealion II discovered oil-covered survivors on makeshift rafts. Subsequent rescue efforts by multiple submarines saved 150 men, though many others perished after years of brutal captivity and forced labor on the Burma-Siam railroad.

The Logistics of Victory

Behind frontline operations, a massive support infrastructure developed. Admiral Charles Lockwood pushed for advanced bases at Guam, envisioning submarine tenders, repair facilities, and even a rest camp amidst coconut groves. These plans sparked interservice rivalries until Admiral Nimitz personally intervened. The resulting facilities at Apra Harbor allowed submarines to operate deeper in Japanese waters without lengthy returns to Pearl Harbor.

Meanwhile, innovative solutions addressed equipment shortages. Eleven frequency-modulated sonar sets intended for minesweepers were repurposed for submarines, while officers like Commander “Dan” Daspit worked to accelerate delivery of critical systems.

Tactical Evolution and Notable Engagements

Submarine warfare reached new levels of sophistication in 1944. The USS Hardhead’s attack on the Japanese cruiser Natori demonstrated improved torpedo tactics, while the USS Croaker scored a remarkable first-patrol success by sinking the light cruiser Nagara off Nagasaki.

Perhaps most dramatically, the USS Barb under Commander Eugene Fluckey sank the 20,000-ton escort carrier Unyo and oil tanker Azusa Maru in a single bold surface attack. Fluckey’s innovative tactics – using a larger ship as background to mask his approach – exemplified the growing confidence and skill of American submariners.

The Balance Sheet of War

By September 1944, American submarines had fundamentally altered the Pacific War’s logistics. The Joint Army-Navy Assessment Committee credited them with sinking 41 merchant ships (215,657 tons) and 14 warships (41,089 tons) that August alone. Targets included vital oil tankers, further strangling Japan’s fuel supplies.

Yet these successes came at cost. The loss of submarines like the Robalo (disappeared near Palawan) and Flier (struck a mine in Balabac Strait) reminded crews of their vulnerability. Survivors’ accounts – like those from the Flier, where only eight men escaped the sinking – underscored the war’s human toll.

As Admiral Lockwood reflected, the silent service had become “the decisive factor” in the Pacific, though its contributions would remain less visible than carrier battles or island campaigns. The submarines’ unrelenting pressure on Japanese shipping lanes constituted economic warfare on a grand scale, systematically dismantling Japan’s ability to sustain its far-flung empire and military machine. By 1944, this campaign had reached its devastating crescendo.