Engineers Called His B-25 Gunship “Impossible” — Until It Sank 12 Japanese Ships in 3 Days

At 7:42 a.m. on August 17th, 1942, Captain Paul Irvin Gunn crouched under the wing of a Douglas A-20 Havoc at Eagle Farm Airfield near Brisbane. He watched intently as two air depot mechanics welded heavy steel brackets into the bomber’s glass nose, right where the bombardier used to sit.
At forty-three years old, Gunn possessed twenty-one years of naval aviation service, a relentless mechanical intellect, and a heart weighed down by intolerable agony. His beloved wife, Polly, and their four young children were currently trapped in the brutal Japanese Santo Tomas internment camp in Manila.
Every single minute he spent away from the frontline felt like a direct betrayal of his family, yet the Allied war effort in the Southwest Pacific was teetering on the precipice of absolute disaster.

The newly formed Fifth Air Force was losing medium bombers far faster than factory replacements could ever arrive from the United States. In July alone, the Third Attack Group had lost eleven A-20s while attempting to strike Japanese troop convoys from high altitude.
High-altitude bombardiers simply could not hit fast, maneuvering enemy vessels navigating open waters. When the pilots dropped lower to improve their precision, dense anti-aircraft deck fire from destroyers shredded the unarmored airframes.
Captain Ed Larner had watched three of his best aircrews burn in the waters of the Coral Sea during the previous week alone. Japanese naval forces were reinforcing their garrisons across New Guinea completely at will.

Paul Gunn had a radical idea that defied standard military aviation doctrine. He believed that if bombers flew at treetop level and skipped bombs across the surface of the water like flat stones, they could hit enemy ships at point-blank range.
However, to make such an approach survivable, the attacking aircraft had to overwhelm the ship’s anti-aircraft gunners with ferocious, uninterrupted forward firepower. They needed to turn light bombers into relentless, heavily armed strafers.
The core engineering problem facing Gunn was deceptively simple. The standard A-20 Havoc carried only four rifle-caliber .30-caliber machine guns in its nose, which lacked stopping power.

Those .30-caliber rounds bounced harmlessly off Japanese ship armor like light hail against a tin roof. Gunn knew he needed heavy .50-caliber aircraft machine guns, and he needed four of them mounted directly in the forward nose compartment.
He envisioned four heavy barrels firing straight ahead, delivering a combined rate of fire exceeding 1,700 rounds per minute. General George Kenney, the aggressive new commander of the Fifth Air Force, granted Gunn exactly one week to prove his concept.
Working without official schematics, Gunn scavenged .50-caliber machine guns from wrecked P-39 Airacobras and P-40 Warhawks scattered across Australian airfield boneyards. The fighter planes were beyond repair, and their pilots were dead, but the guns were still fully functional.

Gunn mounted the heavy weapons onto a custom-built steel frame welded directly inside the empty nose compartment of an A-20. Each Browning .50-caliber gun weighed sixty-four pounds, and the four thousand rounds of belted ammunition added over two hundred additional pounds.
This massive concentration of weight shifted the aircraft’s center of gravity drastically forward. During the initial test flight, the nose-heavy bomber nearly plunged straight into the tarmac, forcing the test pilot to fight the controls continuously.
The A-20 barely managed to climb out of Eagle Farm and continuously threatened to nose over into a fatal dive. Unfazed, Gunn spent two sleepless days rebalancing the entire airframe by stripping non-essential equipment and adjusting the tail trim.

When the second test pilot landed the modified Havoc, he reported that the plane flew like it was furious, but it remained fully controllable. General Kenney immediately gave his approval for field trials.
On September 12th, sixteen modified A-20 strafers launched a sudden strike against the strategic Japanese airfield at Buna. The strafers swept in over the jungle canopy at treetop level with all forward guns hammering in a deafening crescendo.
They destroyed fourteen enemy aircraft on the ground and completely suppressed every anti-aircraft position in the area without losing a single A-20. It was a stunning tactical success, but Kenney realized the A-20 lacked the range to strike deep into enemy territory across the jagged Owen Stanley Mountains.

Furthermore, the A-20’s bomb payload was too limited to destroy heavy naval vessels. Gunn needed a significantly larger airframe, and his eyes turned toward the North American B-25 Mitchell medium bomber.
The B-25 offered far greater range, a heavier bomb capacity, and a spacious fuselage that could accommodate an extraordinary amount of weaponry. In December 1942, Gunn removed the bombardier glass and nose guns from a B-25C model.
He installed four .50-caliber machine guns directly in the nose, added four additional guns in external cheek packages along the fuselage, and fixed the top turret to fire straight ahead.

This initial layout yielded ten forward-firing heavy machine guns, but Gunn refused to stop there. He added two additional cheek guns on each side, bringing the grand total to fourteen forward-firing .50-caliber guns.
When all fourteen guns fired simultaneously, they unleashed two hundred and fifteen pounds of heavy lead into a target every single second. Skeptical ground crews dubbed the bizarre, top-heavy creation “Papy’s Folly,” doubting it could ever fly safely.
Gunn personally flew the prototype down to Charters Towers to demonstrate its capabilities to the pilots of the Third Attack Group. The aircraft was undeniably nose-heavy, requiring maximum backward pressure on the control stick just to remain level during takeoff.

Once airborne, however, the heavily modified B-25 transformed into an unstoppable, fire-breathing commerce destroyer. Astonished by the firepower, General Kenney immediately ordered twelve more B-25 conversions to be completed without delay.
The airmen of the 81st Air Depot Group in Townsville worked grueling eighteen-hour shifts, cutting sheet metal and welding mounts for every available B-25. By February 1943, thirty fully operational strafers were parked on the ramps, ready for combat operations.
Meanwhile, Kenney had sent Gunn’s detailed hand-drawn engineering blueprints to the Army Air Forces technical headquarters at Wright Field in Ohio. The high-ranking engineers at Wright Field spent three days conducting theoretical stress calculations before issuing an urgent official cable to Australia.

The engineers declared Gunn’s field modifications completely impractical, warning that the severe weight imbalance would cause structural failure. They claimed the aircraft would be far too heavy, impossible to control, and should be grounded immediately for safety.
General Kenney happened to be visiting Washington, D.C., when the alarming message from Wright Field was formally delivered. He walked directly into the office of General Henry “Hap” Arnold, where the technical engineers were waiting to explain why Gunn’s design was impossible.
Kenney listened patiently before informing the room that twelve of those supposedly impossible aircraft had just destroyed an entire Japanese convoy in the Bismarck Sea. Every single enemy transport had been sent to the bottom, and sixty more strafers were currently being converted down under.

General Arnold promptly dismissed the embarrassed engineers from his office, giving Kenney full authority to proceed with the modification program. The legendary Battle of the Bismarck Sea had commenced on February 28th, 1943, following critical intelligence intercepts.
Allied codebreakers stationed in Melbourne had successfully decrypted secret Japanese naval transmissions detailing a major reinforcement operation. A massive troop convoy was departing the primary Japanese stronghold at Rabaul, bound for Lae on the northern coast of New Guinea.
The convoy comprised eight heavily laden transport ships escorted by eight modern destroyers, carrying nearly seven thousand imperial troops. General Kenney was given seventy-two hours to coordinate a strike force and stop the convoy before it reached its destination.

The projected route required the Japanese fleet to cross four hundred miles of open ocean across the treacherous Bismarck Sea. Imperial Japanese commanders were confident that severe weather conditions would shield their ships from effective Allied air observation.
March represented the height of the monsoon season in the Southwest Pacific, bringing low-hanging cloud decks, torrential downpours, and terrible visibility. Japanese naval doctrine assumed high-altitude Allied bombers could never hit maneuvering ships through heavy cloud cover.
While the Japanese commanders were correct about the storm clouds, they drastically underestimated the revolutionary tactics about to be unleashed. On March 2nd, an Allied reconnaissance patrol spotted the convoy steaming south through the strategic Vitiaz Strait.

A formation of high-altitude B-17 Flying Fortresses dropped one hundred and thirty-seven heavy bombs through breaks in the clouds. Although the aircrews claimed multiple direct hits, subsequent analysis revealed that high-altitude bombing against fast-moving ships had failed completely.
The Japanese convoy continued its southward advance unhindered, hugging the rugged coast of New Guinea under cover of night. Japanese commanders anticipated reaching Lae by dawn on March 4th to unload troops under the protective umbrella of land-based Zero fighters.
They had no inkling that a customized fleet of low-altitude strafers was preparing to launch from airfields across the mountains. On the evening of March 2nd, Captain Ed Larner briefed the nervous pilots of the 90th Bomb Squadron at Port Moresby.

The strike force consisted of twelve B-25 strafers, thirty modified A-20 Havocs, Royal Australian Air Force Beaufighters, and P-38 Lightnings for high cover. The strafers were instructed to attack at masthead height, skimming the waves just fifty feet above the water at point-blank range.
The tactical objective was clear: saturate the enemy deck guns with devastating machine-gun fire, skip bombs into the hulls, and escape before fighters reacted. Larner candidly admitted to his men that they had only practiced the dangerous skip-bombing maneuver once during training exercises.
When a young navigator asked what would happen if an aircraft took heavy anti-aircraft fire on the final approach, Larner replied simply that they would find out tomorrow. The briefing adjourned at 2200 hours, and virtually no one slept as the mechanics performed final arming checks.

At 0630 hours on March 3rd, 1943, a massive Allied strike force of one hundred and thirty-seven aircraft assembled over Cape Ward Hunt. B-17s initiated the raid from high altitude to draw the enemy anti-aircraft fire upward toward the clouds.
Moments later, Larner led the low-level B-25 strafers in from the southeast, flying mere feet above the crests of the ocean waves. Twelve strafers aligned side by side, creating a continuous, three-hundred-yard-wide wall of flying steel.
The combined forward armaments of the twelve aircraft unleashed one hundred and sixty-eight heavy .50-caliber machine guns simultaneously. The crew of the Japanese transport Kyokusei Maru spotted the approaching low-level bombers when they were just two miles away.

The transport’s captain immediately ordered hard to starboard, but the massive ship responded far too slowly to avoid the attack. At eight hundred yards, the B-25s opened fire, their tracer rounds chewing across the water like a giant mechanical saw.
The concentrated fire shredded the ship’s wooden superstructure, destroyed the bridge, and annihilated the anti-aircraft gun crews before they could aim. Three B-25s released their heavy five-hundred-pound demolition bombs at a distance of just one hundred yards.
The first bomb skipped cleanly off the water, smashed through the steel hull below the waterline, and detonated inside the main engine room. The second bomb struck amidships, causing catastrophic internal explosions that tore the transport apart from within.

Within thirty seconds of the strafers’ arrival, Kyokusei Maru was dead in the water, enveloped in thick black smoke and listing sharply to port. The burning transport sank beneath the waves forty minutes later, leaving oil slicks and debris scattered across the sea.
Seeing the disaster, the transport Taiyo Maru attempted to escape at its maximum speed of fifteen knots. The approaching B-25 strafers were cruising at two hundred and forty knots, making escape mathematically impossible.
Four strafers bracketed Taiyo Maru from both flanks, converging their tracer streams directly onto the crowded decks of the vessel. Anti-aircraft crews were cut down instantly, the bridge windows shattered, and the ship’s executive officer was killed on the spot.

Eight delayed-action bombs were released at masthead height, five of which detonated directly inside the troop-laden holds of the transport. The steel hull split open, and the ship sank in less than six minutes, dragging hundreds of fully equipped soldiers beneath the waves.
Simultaneously, Australian Beaufighters raked the deck of the destroyer Shikishima as it attempted to provide defensive smoke screens. Though anti-aircraft fire struck one Beaufighter, the pilot maintained his course, riddling the destroyer’s deck from bow to stern.
When the B-25 strafers made their run, Shikishima was left with virtually no operational defensive firepower to counter the low-altitude strike. Three strafers attacked from multiple vectors, dropping bombs that ripped open the destroyer’s port side and engine compartments.

By 0900 hours on March 3rd, the Japanese reinforcement convoy had been completely shattered and scattered across forty square miles of ocean. Five transports were sinking or engulfed in flames, while two destroyers were heavily damaged and drifting helplessly.
The surviving vessels attempted to flee toward Lae, but the relentless strafers returned at 1400 hours with fresh ammunition and bomb loads. The Japanese ships had no air support, as their escorting Zero fighters had been forced to land at Lae to refuel.
During the afternoon wave, the transport Oidogawa Maru absorbed twelve direct bomb hits, triggering a massive explosion in its main magazine. The resulting fireball was visible from Port Moresby, over one hundred and thirty miles away across the high mountain range.

When the massive cloud of smoke finally cleared, nothing remained of Oidogawa Maru except a widening circle of burning oil. Eighteen hundred Japanese troops perished in a matter of seconds, leaving no surviving wreckage or lifeboats behind.
Captain Larner brought his strafer in low over the transport Otawa Maru, where his co-pilot counted fourteen separate fires burning on deck. The ship’s anti-aircraft weapons were silent, and Larner’s bombardier dropped two bombs at point-blank range, capsizing the vessel.
Modified A-20 Havocs relentlessly hunted the crippled destroyers, striking the Asashio as her crew attempted to rescue survivors from the water. Three A-20s dropped their payloads across the destroyer’s forward deck, leaving it burning fiercely until it sank at dawn the following morning.

By the evening of March 3rd, the entire Japanese reinforcement fleet had been utterly obliterated in one of the most decisive air battles in history. All eight transports and four destroyers were resting on the ocean floor, ending Tokyo’s ability to reinforce New Guinea by sea.
Of the nearly seven thousand Japanese troops who had departed Rabaul, fewer than twelve hundred managed to reach the shores of Lae. Allied casualties were astonishingly light: just four aircraft were lost, including one B-17 and three P-38 fighters, with thirteen airmen killed.
General Douglas MacArthur triumphantly declared the strike to be one of the most complete and annihilating air combats ever recorded. The Japanese Navy never again attempted to send vulnerable troop transports into the Bismarck Sea without overwhelming air superiority.

While Allied forces celebrated the stunning victory, back in Ohio, Wright Field engineers were finishing their formal report on why the B-25 modifications were impossible. On March 5th, General Kenney sent a brief, triumphant message directly to General Hap Arnold in Washington.
The cable requested the immediate factory integration of Gunn’s forward gun package into all future production models of the B-25. Arnold immediately telephoned J.H. “Dutch” Kindelberger, the president of North American Aviation, demanding instant factory re-tooling.
Kindelberger insisted that his senior aircraft engineers needed to examine the physical modifications before altering the active production line. Arnold replied that he was sending the very man who had designed them, ordering Paul Gunn to report to California immediately.

Gunn received the assignment with mixed emotions, as he desperately wanted to remain in the Pacific theater near his captive family. His wife and four children had been languishing in the brutal Santo Tomas internment camp for fourteen agonizing months.
Every combat mission Gunn flew felt like a small step closer to the eventual liberation of the Philippine Islands. Relocating to California meant traveling thousands of miles away from the theater of operations in the wrong direction.
General Kenney made it a direct military order, emphasizing that the Fifth Air Force required hundreds of factory-built strafers to win the war. Kenney promised Gunn that he would be back in the Pacific within six weeks if he completed the technical transition quickly.

Paul Gunn arrived at the massive North American Aviation facility in Long Beach, California, on March 27th, 1943. The plant spanned one hundred and forty acres, employing twenty thousand aircraft workers operating on continuous three-shift schedules.
Factory engineers meticulously reviewed Gunn’s hand-drawn, blood-stained blueprints and immediately asked to see his formal structural stress calculations. Gunn chuckled and replied that he didn’t have any, explaining that he had tested the design simply by flying it into combat.
When engineers expressed concern that muzzle blasts from the cheek guns would buckle the aluminum skin, Gunn acknowledged that it had indeed happened. He then showed them the custom blast tubes he had welded to extend beyond the propeller arc, completely solving the structural issue.

For two weeks, team engineers worked alongside Gunn to reverse-engineer his battlefield modifications into standardized factory technical drawings. They reinforced the internal nose framing, redesigned the heavy gun mounts, and adjusted the trim controls to balance the weight shift precisely.
On May 10th, 1943, the first factory-built B-25G Strafer rolled off the assembly line, featuring four .50-caliber nose guns and a 75mm cannon. The massive artillery cannon utilized the same heavy ammunition as the Army’s M3 Lee tank, capable of holing a destroyer hull.
When Gunn test-flew the prototype, the 75mm cannon recoiled four full feet upon firing, causing the entire airframe to shudder violently. The navigator was required to manually reload the heavy cannon between shots, resulting in a slow firing rate of one round every thirty seconds.

Gunn reported that while the cannon was effective against large ships, it was far too slow for fast-moving tactical targets. North American Aviation responded by designing the improved B-25H model, which featured fourteen forward-firing .50-caliber machine guns alongside an upgraded cannon.
This evolved into the legendary B-25J model, which removed the heavy cannon entirely and added four additional .50-caliber machine guns. With eighteen forward-firing heavy guns, the B-25J became the most heavily armed production bomber manufactured during the Second World War.
Over four thousand nine hundred B-25J strafers were produced, with the first production models arriving in the Pacific theater by October 1943. True to his word, General Kenney brought Gunn back to Australia in May 1943, exactly six weeks after he had departed.

Upon his return, Gunn immediately rejoined the Fifth Air Force, constantly refining maintenance procedures and inventing new armaments for the fleet. In April 1943, B-25 strafers destroyed sixteen Japanese supply barges near Finchhafen, followed by sinking twelve cargo vessels at Wewak Harbor.
The relentless pressure forced the Japanese military to abandon daylight naval resupply operations across the entire Southwest Pacific region. In response, Gunn helped aircrews adapt radar systems to conduct lethal skip-bombing strikes against enemy shipping in total darkness.
Japanese sailors quickly learned to dread the low-flying medium bombers, bestowing upon the modified B-25s the terrifying moniker “The Black Death.” On November 2nd, 1943, Major Ben Fridge led fifty-nine B-25 strafers in a devastating low-level raid on Rabaul Harbor.

Skimming the water through dense phosphorus smoke, the strafers struck thirty vessels, sinking five and heavily damaging twelve others in fifteen minutes. Rabaul Harbor was permanently neutralized as a forward Japanese naval base, crippling Tokyo’s defense perimeter in the Pacific.
Gunn personally flew on that dangerous mission despite his advanced age of forty-four and his staff position as a special projects officer. He refused to remain behind at headquarters while his family suffered deteriorating conditions inside the Manila internment camp.
Intelligence reports indicated that food rations at Santo Tomas had been severely cut, causing widespread malnutrition and disease among the captives. Worse, rumors circulated that the Japanese camp commanders planned to execute all civilian prisoners if Allied forces approached Manila.

Gunn repeatedly pleaded with General Kenney to let him fly on the initial strike over Manila when the liberation campaign finally commenced. Kenney granted the request, knowing that no officer had sacrificed more or worked harder to make the Philippine campaign possible.
Throughout 1944, Fifth Air Force strafers continued to dominate the skies, destroying nearly one thousand enemy aircraft on the ground. They sank over two hundred and seventy ships and eliminated tens of thousands of enemy soldiers across New Guinea and the East Indies.
Gunn constantly added new field modifications, mounting extra fuel tanks, installing rocket launchers, and improving gun-cooling systems between missions. On October 20th, 1944, General MacArthur’s forces successfully landed at Leyte, bringing the liberation of Manila within reach.

Gunn flew multiple combat missions daily, pushing himself to the absolute limit of physical endurance as the fighting intensified around Leyte. Tragic disaster struck on November 27th, 1944, when fifty-six Japanese bombers launched a surprise nighttime raid on Tacloban Airfield.
Gunn was inside the operations tent reviewing flight plans when heavy fragmentation bombs detonated just two hundred yards from the runway. The powerful blast wave knocked him unconscious, and jagged bomb shrapnel tore through his left leg and shoulder, severing an artery.
When medical personnel arrived, Gunn was bleeding profusely but stubbornly trying to stand up to inspect his damaged airframes. The surgeon performed emergency surgery to save his leg, informing Gunn that he would be bedridden for at least six months.

Despite facing medical retirement after twenty-six years of honorable service, Gunn refused to be evacuated to the United States. He insisted on remaining in the Philippines, vowing that he would not leave until he held his family in his arms again.
The brutal Battle of Manila began on February 3rd, 1945, as American troops fought block by block against fanatic Japanese defenders. That same afternoon, forward units of the 1st Cavalry Division smashed through the gates of Santo Tomas, liberating three thousand seven hundred prisoners.
Against strict medical orders, Gunn obtained a transport flight to Manila on February 4th, leaning heavily on a cane over his bandaged leg. He walked into the makeshift military hospital at Santo Tomas, his heart pounding as he searched the crowded wards for his loved ones.

When he finally located his family, his wife, Polly, did not recognize him at first glance due to his gaunt appearance. Gunn had lost over forty pounds, and his hair had turned completely white from the overwhelming strain of the war.
It was only when he spoke her name that Polly realized the battered officer standing before her was her long-lost husband. His family had survived unimaginable horrors: Polly weighed just eighty-nine pounds, his daughters were severely malnourished, and his son was suffering from malaria.
The emotional family reunion lasted four short hours before Gunn returned to his duty station, knowing the war was not yet finished. The modified B-25 strafers he had created continued to sweep the skies until Japan formally surrendered in August 1945.

By the war’s end, Gunn’s strafer concept was officially credited with sinking over eight hundred Japanese ships and destroying two thousand aircraft. The commerce destroyer idea that military engineers had once dismissed as impossible had proven to be the single most effective anti-shipping weapon.
Gunn retired from the military as a full colonel in 1948, returning to Manila to rebuild Philippine Airlines, which he had founded before the war. Operating surplus C-47 transports, he expanded the carrier into a thriving international airline connecting major cities across Asia and North America.
In recognition of his extraordinary contributions to aviation and national defense, the Philippine government awarded Gunn the Distinguished Service Star in 1947. General George Kenney later wrote in his memoirs that “Papy” Gunn was unequivocally the most valuable individual officer in the Fifth Air Force.

Tragically, on October 11th, 1957, Paul Gunn perished when his twin-engine aircraft encountered severe turbulence and crashed into a mountain ridge near Baguio. He was fifty-seven years old, leaving behind a monumental legacy that permanently transformed modern air warfare and saved countless lives.
The low-altitude strafing tactics and forward-firing gun packages Gunn pioneered directly influenced the design of legendary modern aircraft like the AC-130 gunship and the A-10 Warthog. His unyielding determination, mechanical brilliance, and profound love for his family remain an enduring inspiration to generations of aviators around the world.