The Underwater Arms Race of World War II

As the war in the Pacific intensified, American submarine forces found themselves engaged in a deadly technological chess match with Imperial Japan. The quiet depths became a battleground of innovation where electronic warfare, radar advancements, and torpedo improvements would determine victory. This underwater conflict represented more than just sinking ships—it was a test of engineering ingenuity, tactical adaptation, and human endurance under the immense pressure of the deep.

The Japanese Navy, though technologically behind in several areas, proved surprisingly adept at certain forms of electronic warfare. Their radio jamming operations initially disrupted American submarine communications, particularly when U.S. boats transmitted near Japanese stations. However, American countermeasures developed with remarkable speed—within about a week of encountering the interference, the submarine force implemented frequency-hopping technology that rendered Japanese efforts largely ineffective.

The Electronic Battle Beneath the Waves

Radio direction finding became a crucial tool in this undersea conflict. While Japanese attempts at locating American submarines through radio transmissions proved futile (partly because wolf packs communicated through specialized frequencies), Allied direction-finding systems in the Atlantic had already demonstrated their devastating effectiveness against German U-boats. The technological gap was significant—Japanese radar and electronic equipment consistently lagged about a year behind American developments.

Early in the war, submarine crews treated radio use with extreme caution, fearing that any transmission might bring enemy aircraft down upon them. But as experience grew, so did confidence. By mid-war, American submarines communicated freely, even sending weather reports from near enemy shores without reprisal. These reports proved invaluable for coordinating air strikes, amphibious landings, and naval bombardments.

Night Vision and Deception Technologies

One of the most pressing technological challenges involved night operations. Standard attack periscopes provided poor visibility after dark except during moonlit nights. While some foreign navies had developed specialized night periscopes, their 9-inch diameter designs were deemed impractical for American submarines because they couldn’t double as emergency daytime periscopes. Months of discussions at the Bureau of Ships eventually led to a solution—incorporating radar antennas into periscopes primarily designed for daytime ranging.

Another critical development involved underwater deception devices—equipment to confuse and misdirect enemy antisubmarine forces. Reports indicated the Germans were effectively using bubble-making machines in the Atlantic to create underwater screens for evasion. The U.S. Navy urgently needed similar capabilities, especially as submarine losses mounted. A simple bubble-generating device could provide temporary protection until more sophisticated systems were developed.

The Mare Island Conference: Coordinating Technological Advancements

In December 1943, key submarine officers gathered at Mare Island for a crucial conference on underwater warfare technology. Representatives from Washington’s naval bureaus, Portsmouth Navy Yard, Electric Boat Company, and retired officers collaborated to address pressing issues. The meetings, organized into specialized committees, produced remarkable results fueled by shared determination to win the war.

Night periscope specifications and ST-type radar designs received top priority. The Bureau of Ships committed to delivering functional equipment within nine months, with prototype installations on the USS Sea Fox (SS-402) promised in seven. Another victory came with the announcement that a new 5-inch deck gun was ready for installation on all fleet submarines.

The only unresolved project involved submarine protection systems—those deceptive devices to counter antisubmarine attacks. The proposed solution required installing new tubular devices on modified hull structures, meaning extensive yard periods for each boat. Naval laboratories in San Diego reported promising progress, offering hope for near-term deployment.

Life and Death in the Silent Service

The human cost of this technological war became painfully clear with losses like the USS Capelin (SS-289), which failed to return from patrol in the Southwest Pacific. Presumed lost, possibly to minefields, her disappearance left no postwar traces—a sobering reminder of the risks submariners faced daily.

Maintenance and support infrastructure struggled to keep pace with the expanding submarine force. Facilities at Mare Island, Hunter’s Point, and Bethlehem Steel Company performed admirably under officers like Commander Joe Fowler and Commander “Rim” Rawlings. But planners recognized that Pearl Harbor’s overwhelmed shipyards couldn’t handle all necessary repairs, especially for boats needing extensive work after severe damage. A system emerged where Pearl Harbor handled routine maintenance while major repairs went to Portsmouth, New Hampshire.

Breakthrough Technologies Reach the Front

By early 1944, several critical technologies began reaching operational boats. The USS Spadefish (SS-411) became the first submarine scheduled to receive the new FM sonar, whose mine-detection capabilities promised to save countless lives. Silent depth detectors—nicknamed “Susie”—allowed safe sounding near enemy shores without alerting Japanese listening devices. Electric torpedoes, addressing earlier reliability issues, were being installed in stern torpedo rooms, with eight carried by boats like the USS Seahorse (SS-304) and USS Angler (SS-240).

The first IFF (Identification Friend or Foe) equipment arrived on the USS Angler, though with mixed results. The system worked well when remembered—a significant “if” since operators had to manually activate it. Several friendly fire incidents occurred at Pearl Harbor when approaching pilots forgot to switch on their IFF. Later intelligence suggested the Japanese captured some units and used them against Allied forces, contributing to tragic incidents like the USS Guardfish (SS-217) sinking a U.S. fleet repair ship in 1945.

Legendary Patrols and Tactical Innovations

The war produced legendary submarine commanders whose exploits demonstrated both courage and evolving tactics. Commander R.E.M. “Bob” Ward of the USS Sailfish (SS-192) engaged in a dramatic ten-hour battle with a Japanese carrier group near Tokyo Bay in December 1943. Fighting through typhoon conditions with 40-50 knot winds, Ward’s crew detected radar contacts that eventually revealed two large and two small targets.

Despite the submarine’s inability to exceed 12 knots in the heavy seas (while the targets made 18), Ward pressed the attack. After a close encounter with a destroyer at 400 yards, the Sailfish fired a spread of four torpedoes at 2,100 yards, hearing two hits. Surviving a 21-depth charge counterattack, Ward pursued and eventually sank what was identified as the Japanese carrier Chuyo—unbeknownst to him carrying American POWs from the USS Sculpin (SS-191). This action earned Ward the Navy Cross and his crew the Presidential Unit Citation.

Equally dramatic was the USS Gato’s (SS-212) seventh patrol in December 1943. After attacking a convoy near Brisbane, Commander R.J. Foley’s boat endured accurate depth charging that left an unexploded depth charge lodged on its deck when it surfaced. Foley’s ingenious solution—placing the bomb on a slowly deflating rubber raft set adrift behind them—became submarine legend.

The Gato later made history again by successfully defending against a Japanese “Jake” floatplane with its deck guns—an encounter that troubled senior commanders despite its successful outcome. While submarine-aircraft gun battles were discouraged, the incident highlighted ongoing questions about submarine antiaircraft defenses.

The Statistical Tide Turns

By late 1943, American submarine effectiveness reached new heights. December saw 22 submarines sink 29 merchant ships (127,000 tons) plus three warships (22,000 tons). The annual total reached 308 merchant vessels (1,366,962 tons) and 22 warships (43,597 tons). Standout performers included the USS Flying Fish (SS-229) under Commander Donaho, sinking an 8,600-ton freighter and 10,200-ton tanker in the South China Sea, and the USS Galaxias (SS-371) sinking three ships in one night.

January 1944 nearly doubled December’s totals—35 submarines (including the British HMS Tally-ho) sank 53 merchants (154,400 tons), one light cruiser, two destroyers, and one minelayer. Particularly significant were eight oil tankers, bringing the war’s total to 30—a critical blow to Japan’s smaller tanker fleet and its oil-starved war machine.

Commander “Dusty” Dornin of the USS Trigger (SS-237) accounted for the month’s largest kill—the 11,933-ton submarine tender Heian Maru—during an attack on a Truk-bound convoy. In a daring close-range approach, Trigger came within 700 yards of an escorting destroyer that never detected her until four bow torpedoes struck home.

Preparing for the Marianas

As Admiral Spruance planned bold moves against the Marianas, submarines played crucial roles in reconnaissance and lifeguard duties. The attack on Saipan followed the successful Truk model, with submarines like the USS Sunfish (SS-281), USS Tang (SS-306), and USS Peto (SS-265) positioned to intercept fleeing Japanese forces.

The Tang, under Commander Richard O’Kane (a veteran of the USS Wahoo under the legendary “Mush” Morton), particularly distinguished itself during this operation. On its first patrol as a new boat, Tang sank five ships—an impressive debut that foreshadowed its record-setting career.

The Human Element: Morale and Recognition

Amid the technological and tactical developments, submarine force morale received a boost from unexpected quarters. In February 1944, Commander “Eddie” Peabody arrived at Pearl Harbor with musical talents and entertainment groups he’d organized in the Great Lakes. These performers brought vital relief to submariners returning from stressful patrols.

Admiral Nimitz personally awarded 18 medals at a submarine base ceremony aboard the USS Tullibee (SS-284). The event recognized extraordinary achievements, including a second Navy Cross for the USS Wahoo’s Morton. In a surprise move, Nimitz awarded the Legion of Merit to the submarine force commander for experimental programs that dramatically improved torpedo performance and combat effectiveness.

The statistics proved the point—torpedo hit rates had soared from about 20% early in the war to 45.6% by early 1944 (220 hits out of 482 torpedoes fired in December 1943-January 1944). This improvement reflected both technological advances and hard-won operational experience.

The Tide Turns: February 1944’s Strategic Gains

February 1944 marked a turning point in the Pacific. American forces seized the Admiralty Islands a month ahead of schedule, isolating Japanese strongholds at Rabaul and Kavieng. Combined with the capture of the Marshalls, bombardment of Truk and Saipan, and neutralization of Eniwetok, Japan’s defensive perimeter collapsed.

Submarine contributions to this success were immense. Twenty-three American submarines sent 51 merchant ships (including nine vital oil tankers totaling 231,002 tons) to the bottom, along with one light cruiser, two destroyers, and one submarine. Top performers included:

– USS Grayback (SS-208) under Commander J.A. Moore (four ships, 21,594 tons)—though lost with all hands
– USS Tang (SS-306) under Commander O’Kane (21,429 tons)
– USS Peto (SS-265) under Commander R.M. Metcalf (five ships, 21,152 tons)
– USS Jack (SS-259) under Commander T.M. Dykers (four tankers in one day)

The Jack’s patrol included extraordinary heroism when Chief Motor Machinist’s Mate Earl M. Archer crawled 100 feet through a narrow, flooding induction pipe to plug leaks—an act that likely saved the boat during subsequent depth charging.

Conclusion: The Silent Victory

By early 1944, American submarines had transformed from cautious hunters into a dominant force that strangled Japan’s maritime lifelines. This success resulted from relentless technological innovation, tactical adaptation, and the courage of submariners who operated in what one officer called “a private war” across the Pacific’s vast expanses.

The submarine campaign demonstrated how specialized warfare could achieve strategic effects disproportionate to the number of vessels involved. While surface fleets and carrier task forces captured headlines, submarines quietly eroded Japan’s ability to wage war by sinking merchant tonnage faster than it could be replaced. Their story remains one of World War II’s most remarkable—and least visible—triumphs.