Dispatch: U.S. Military History Magazine

Welcome to Arsenal, where the weapons and war machines of military history come to life. Today we explore the Gato and Balao class submarines in the Pacific undersea campaign of World War Two, and the crews and opponents who gave them their reputation. A longer version of this feature, with fact sheets and photos, is available in the print edition on LinkedIn or by email. If you enjoy learning how technology, tactics, and human decisions come together in combat, you can find more articles, podcasts, and resources at Trackpads dot com.

Arsenal is the Friday feature of Dispatch: United States Military History Magazine. Our story opens in the black, restless sea off Luzon, where a Japanese convoy pushes north toward the home islands. On the surface, a Balao class fleet submarine runs low and fast, deck awash and bridge crowded with bundled lookouts and the attack party. Dawn is only a faint orange edge in the east. For now, the boat is wrapped in darkness while men study radar scopes and bearing indicators, turning small signals into range, angle, and timing.

Down below, the control room is hot and tight. Men crowd around the plotting table, following the zigzag of a freighter guarded by nervous escorts. The air carries diesel fuel, coffee, sweat, and metal. Orders move quickly but quietly: come left to a new course, ahead full, open outer doors forward. In the bow room, torpedomen stand ready beside Mark fourteen and Mark eighteen torpedoes, waiting for words they have practiced in drills and heard only a few times in real war.

The skipper chooses to fight on the surface, using the boat’s speed in the cool predawn air. He swings across the convoy’s path to cross the T, lining up a bow shot that will send a fan of torpedoes into the formation. When the range and angle are right, the boat seems silent for a heartbeat. Then the order comes: fire one, fire two, fire three, fire four. The hull shudders as compressed air kicks the torpedoes into the sea.

Seconds stretch as the submarine turns away. Far ahead, fire and water lift a ship out of the night. Then the escorts answer. Searchlights stab the dark, tracers hunt the low silhouette, and the bridge has no time to celebrate. The skipper orders a crash dive. Men tumble below, hatches slam, valves spin, and the submarine angles down. Depth charges detonate overhead, hammering the hull and reminding every man that a few inches of steel separate him from the Pacific.

That single attack is part of a much larger campaign. Between the wars, United States Navy planners suspected any Pacific conflict would be a long range maritime struggle across enormous distances. Older submarines, including small S boats and interwar experiments, lacked the range, reliability, and habitability to cross thousands of miles, patrol for weeks, and still fight. The Navy needed a fleet submarine that could operate far ahead of the battle line, scout, attack, and return without constant support.

Turning that idea into hardware meant solving several problems at once. Designers wanted boats that could travel roughly eleven thousand nautical miles at economical speed and stay out for as long as seventy five days. They needed a heavy torpedo battery, fuel, food, spare parts, and machinery that could endure tropical heat, rough seas, repeated dives, and the pounding of depth charges. Early efforts were imperfect, but each taught lessons about hull form, internal layout, speed, endurance, and reliability.

When war came in nineteen forty one, the planned fleet role changed almost overnight. Instead of scouting for battleships in a set piece engagement, American submarines were ordered into unrestricted war against Japanese shipping. Japan’s empire depended on convoys carrying oil, ore, food, troops, and equipment through choke points such as the South China Sea and Luzon Strait. If those sea lanes could be cut, factories at home would starve and forward armies would feel the pressure.

Forward bases became essential to this campaign. Pearl Harbor, Fremantle, Brisbane, and other ports turned into places where submarines refueled, rearmed, repaired, and took on new intelligence before heading back into enemy waters. The boats might fight alone once on station, but they were supported by a wide network of code breakers, repair crews, supply officers, tenders, and dock workers. Every patrol began long before the submarine cleared the harbor.

The Gato class was the first American fleet submarine to bring the necessary traits together: range, surface speed, torpedo power, and enough internal volume for a large crew on long patrols. The Balao class followed as an evolutionary step, using higher strength steel in the pressure hull so boats could dive deeper and survive heavier attacks. Together, they became the backbone of a campaign that sank millions of tons of Japanese merchant and naval shipping and slowly severed the arteries of an island empire.

The Gato design grew from interwar experiments, not sudden inspiration. Designers studied earlier long range boats and built a stronger, bigger submarine with a full double hull, ample fuel tanks, and robust diesel engines. Every line reflected a tradeoff. A stronger hull and reserve buoyancy added weight but improved survival and trim. Underwater speed remained modest because long surface cruising mattered more. A taller silhouette made the boats seaworthy in Pacific swells even if it made them easier to see in some conditions.

At a glance, Gato and Balao boats were ocean going attack submarines built for the United States Navy from the early nineteen forties onward. A typical crew numbered around seventy men. The boats carried six forward and four aft torpedo tubes with reloads for repeated attacks. On the surface, they could cross oceans and sprint to firing positions. Submerged, they were limited by battery capacity and air, so a careful skipper treated time underwater as a precious resource.

The visible weapons included a deck gun and light anti-aircraft guns, useful against smaller targets or damaged ships when the air threat allowed. Their real weapon was reach and surprise. A boat could appear in a shipping lane, fire a spread, and vanish below. Shipyards across the United States learned to build these submarines in series. By the middle years of the Pacific war, Gato and Balao boats were sailing steadily from Pearl Harbor, Fremantle, Brisbane, and other bases toward enemy traffic routes.

From the outside, a wartime Gato or Balao looked like a long steel cylinder with a knife like bow and a high angular sail. The main deck ran from bow to stern, broken by the deck gun, fairwater, bridge, and periscope shears. The lines were not graceful like some smaller European submarines, but they were practical. The boats had enough freeboard for heavy seas and enough internal space for fuel, food, torpedoes, batteries, machinery, and the human endurance required for a two month patrol.

The bridge was a compact open platform where the skipper, officers, petty officers, and lookouts searched the horizon during surface running. Below it, the conning tower and control room formed the brain of the submarine. Helmsmen and planesmen handled wheels and levers, the diving officer watched depth and trim, and the plotter turned radar contacts and bearings into an attack picture. Voices stayed calm because they had to. A course change, depth order, or timing mistake could mean a missed shot or a deadly exposure.

Crew spaces were cramped and improvised around machinery and weapons. Bunks were stacked wherever they fit, sometimes over torpedoes in the bow and stern rooms. Many men hot bunked, sharing racks by watch rotation. The atmosphere mixed diesel fumes, oil, rubber, sweat, and cooking smells from a tiny galley that mattered far more than its size suggested. A hot meal could hold morale together during long stretches of boredom, tension, and damp heat.

Aft, the diesel engines thundered during surface running, driving generators that charged the batteries and, when needed, helped turn the shafts. When the order came to dive, engines shut down, clutches disengaged, and electric motors took over. Electricians and machinist’s mates watched switchboards, gauges, and valves, balancing battery draw against the need to keep power in reserve. In the torpedo rooms, torpedomen cared for heavy weapons and prepared the tubes that gave the boat teeth.

Every compartment had a rhythm. Sonarmen listened for the change from merchant screws to an escort’s urgent propeller beat. Radiomen copied coded traffic that could redirect a patrol. The executive officer tracked fuel, food, torpedoes, and the boat’s remaining fight. Life inside a Gato or Balao mixed routine with sudden terror: cards and maintenance one hour, depth charges rattling every fitting the next. To crews, these submarines were cramped, noisy, dangerous homes from which they waged a distant war against ships often seen only as burning silhouettes.

The first wartime patrols came in the worst circumstances. After Pearl Harbor, submarines sailed from Hawaii, the Philippines, and Australia into seas dominated by Japanese aircraft and surface forces. Charts were incomplete, minefields were uncertain, and doctrine was shifting fast. Crews trained for fleet scouting suddenly found themselves hunting troop convoys, tankers, and supply ships headed toward the Philippines, the Indies, and Japan’s forward bases.

A patrol could swing from dull routine to life or death in minutes. Days might pass with maintenance, watch standing, drills, and sleep broken by heat and machinery noise. Then a contact report, radar return, or smoke on the horizon could pull every man into his station. After an attack, the same crew might sit silently through hours of depth charging, counting explosions, listening for leaks, and waiting to learn whether the enemy had lost them.

Those early cruises exposed painful flaws. The Mark fourteen torpedo often ran too deep, failed to detonate, or exploded prematurely. Commanders watched near perfect shots produce only wakes and dull impacts, forcing dangerous second attacks or leaving escorts time to respond. At the same time, Japanese anti-submarine forces improved. Destroyers, patrol craft, seaplanes, and land based aircraft learned to search likely approach routes, punish surfaced submarines, and box in contacts with sonar and depth charge patterns.

Despite those setbacks, the fleet boats slowly turned their design strengths into results. Gatos patrolled from Pearl Harbor across the Marshalls and Carolines and along routes to Truk and Rabaul. Others worked from Australia into the South China Sea, Java Sea, and approaches to Luzon. With better radar and better tactics, skippers embraced night surface attacks, using the submarine like a low, hard to see destroyer that could suddenly disappear below the surface when threatened.

By the time Balao boats joined in numbers, the undersea campaign had matured into a coordinated tonnage war. Loose wolfpack tactics placed two or three boats along the same convoy routes. Intelligence from code breaking and aerial reconnaissance helped guide patrols toward richer targets. The Balao’s deeper diving hull gave commanders more room under heavy depth charge attacks. Ship by ship and convoy by convoy, American submarines strangled Japan’s access to oil, ore, food, and shipping capacity.

To the crews, the strengths were clear. These were dependable long distance machines that could cross the Pacific, patrol for weeks, and still fight on the way home. Their size gave better habitability than many foreign designs, along with space for extra food and spare parts. Radar gave skippers a major advantage in finding targets and avoiding aircraft. The double hull and careful compartmentation gave confidence that the boat could absorb punishment and still return to port.

The boats also gave commanders choices. They could stalk a convoy, shadow it for hours, call in other submarines, attack from ahead, or use the deck gun against smaller targets when conditions allowed. Surface speed at night let them maneuver for position in ways a submerged submarine could not. That ability to choose when to run, dive, track, or attack was one reason fleet boats fit the vast Pacific so well.

The weaknesses were real too. The early torpedo crisis cost opportunities and lives. Even after fixes, submerged endurance was limited by batteries and breathable air. The seaworthy surface profile could make the boats easier for alert lookouts and aircraft to spot. Japanese escorts adapted with sonar, aircraft patrols, minefields, and heavier depth charge patterns. Many Gato and Balao class boats disappeared, and in the tight submarine community, a missing hull number meant dozens of names that would not come home.

Wartime experience constantly changed the boats. High fairwaters and bulky platforms were cut down to reduce silhouette and drag as aircraft became more dangerous. Radar and sonar upgrades added masts and domes that gave the sail a bristling look but improved the crew’s eyes and ears. Better ventilation and air conditioning helped both men and equipment in tropical waters. Fire control gear improved, helping crews turn bearings and ranges into firing solutions faster under stress.

The step from Gato to Balao was structural rather than radical. Higher strength steel and modified hull structure increased test depth, giving skippers more room during depth charge attacks. Late war and postwar Tench class submarines continued the pattern with further refinements. After the war, some boats became radar pickets or training submarines, while others were streamlined for better underwater performance. Through all these changes, the central idea remained recognizable: a long range fleet submarine built to roam far from home and attack an enemy’s lifelines.

The legacy of the Gato and Balao class rests on both record and influence. By the end of World War Two, American submarines, most from this family of fleet boats, had sunk a large share of Japan’s merchant fleet and many warships. They did it with a relatively small force compared with surface fleets and air armadas, proving that endurance, stealth, intelligence, and trained crews could have strategic effect. They helped establish the submarine as more than a tactical ambusher.

Their influence carried into later diesel electric submarines and early nuclear designs. The idea of independent operations thousands of miles from base remained central even as hull shapes and propulsion changed. Human systems carried forward too: watch routines, crew roles, compartment discipline, and the quiet professionalism of submarine service all drew from wartime experience inside these hulls. The technology changed, but the culture of patient, precise, dangerous work endured.

Museum boats help make that inheritance visible. The narrow passageways, torpedo racks, control stations, tiny bunks, and crowded machinery spaces show visitors that the undersea campaign was not an abstract tonnage table. It was a human endurance test inside steel. Standing in one of those compartments makes the scale of the Pacific seem even larger because it reveals how small each crew’s world became once the hatch closed.

Today, several boats from this family survive as museum ships, moored from Pearl Harbor to the American mainland. Visitors can duck through hatches, pass bunks squeezed over torpedoes and batteries, and stand in control rooms crowded with valves, gauges, and memories. For every preserved submarine, many more rest on the ocean floor as war graves. Photographs, film, Dispatch features, and Trackpads audio help connect these boats to individual patrols, lost crews, and the larger Pacific undersea campaign.

Related Dispatch features, Living History interviews, and other Arsenal episodes offer a path deeper into submarine warfare and the Pacific war at sea. However you encounter them, the Gato and Balao class submarines remind us that behind every weapon system are people whose lives depended on machinery, training, judgment, and luck. In the dark waters between attack and counterattack, those factors decided who came home and who remained at sea. You can also hear narrated versions of Arsenal features as part of the Trackpads podcast feeds and Dispatch audio editions.