The Sea Assassin: One “impossible” B-25 modification turned a bomber into the Pacific’s deadliest predator

On August 17, 1942, at Eagle Farm Airfield near Brisbane, Australia, a 43-year-old Captain named Paul “Pappy” Gunn knelt in the dirt beneath the wing of a Douglas A-20 Havoc. He wasn’t looking at blueprints or checking a manual. He was watching a welder fuse four .50-caliber machine guns into the nose of the aircraft—right where the glass for the bombardier was supposed to be.

Pappy Gunn was not a typical officer. He was a 21-year Navy veteran with a singular, burning motivation: his wife and four children were currently held in a Japanese internment camp in Manila. He believed that every Japanese ship he sent to the bottom of the Pacific brought him one mile closer to his family.

At that moment, the Fifth Air Force was losing the war of attrition. High-altitude bombing against moving ships was a failure; bombardiers couldn’t hit a zigzagging destroyer from 10,000 feet. But when they flew lower, Japanese deck gunners tore the bombers to shreds. Pappy Gunn had a radical, almost suicidal solution: turn the bomber into a giant shotgun.

The Birth of the “Strafing Monster”

The logic was simple but the engineering was a nightmare. By packing the nose of a light bomber with heavy machine guns, the pilot could suppress the ship’s anti-aircraft crews during the approach. Then, at the last second, they would “skip” bombs across the water like stones, slamming them into the ship’s hull at point-blank range.

The initial tests nearly ended in disaster. The weight of the four heavy guns and thousands of rounds of ammunition shifted the center of gravity so far forward that the plane refused to climb. It “flew like it was angry,” test pilots reported. Pappy spent 48 hours rebalancing the airframe, moving radio equipment and lead weights to the tail.

On September 12, 1942, his modified A-20s hit the Japanese airfield at Buna. Coming in at treetop level, the “Strafers” destroyed 14 aircraft on the ground and silenced every AA position. Pappy had proven the concept. But he wanted more. He wanted a bigger platform with more teeth. He wanted the B- Mitchell.

The “Impossible” B-25

In December, Pappy moved to the B-25 Mitchell medium bomber. He stripped the nose and installed eight .50-caliber guns. Then he added four more in external “cheek” packs on the fuselage and rotated the top turret forward.

The result was a flying destroyer with 14 forward-firing machine guns, capable of spitting 215 pounds of lead per second. When Pappy sent the blueprints to engineers at Wright Field in Ohio, they officially declared the modification “impossible.” They argued the recoil would rip the nose off the plane or stall the engines.

General George Kenney, commander of the Fifth Air Force, ignored the engineers. He had 12 of Pappy’s “impossible” planes ready just in time for a massive intelligence breakthrough.

The Battle of the Bismarck Sea: 72 Hours of Slaughter

On February 28, 1943, Allied codebreakers intercepted a message: a massive Japanese convoy was leaving Rabaul. Eight transport ships and eight destroyers, carrying 7,000 troops, were bound for Lae, New Guinea. If they arrived, the balance of power in the Pacific would shift.

The convoy commanders banked on the monsoon season. They believed low clouds and heavy rain would hide them from Allied eyes. They were right about the weather, but they were wrong about Pappy’s pilots.

March 3rd: The Low-Level Massacre

At 06:30, 137 Allied aircraft assembled over Cape Ward Hunt. High-altitude B-17s attacked first, forcing the Japanese gunners to look up and fill the sky with high-burst flak. While the Japanese were distracted, Pappy’s Strafers arrived at wave-top height.

The B-25s came in “Line Abreast”—a wall of fire 300 yards wide. On the transport Kyokusei Maru, the captain didn’t even have time to turn his ship. The .50-caliber rounds walked across the water like a chainsaw, shredding the bridge and killing the AA crews before they could even traverse their guns.

Three B-25s dropped their bombs at 100 yards. The bombs skipped off the Pacific swell, slammed into the hull below the waterline, and detonated in the engine room. The ship was dead in the water in 30 seconds.

The carnage continued. The transport Teayo Maru tried to outrun the bombers at 15 knots. The Strafers, doing 240 knots, bracketed the ship from both sides. The lead streams converged on the deck, literally cutting the captain and his officers down in seconds. When the bombs hit, the ship broke in half. Most of the 1,800 soldiers below deck never made it to the surface.

By the evening of March 3rd, the entire convoy was destroyed. Eight transports sunk. Four destroyers sunk. Over 3,000 Japanese troops dead. General Douglas MacArthur called it “one of the most complete and annihilating combats of all time.” The Japanese never again attempted to reinforce New Guinea by convoy.

The 75mm Tank Gun in the Sky

Back in Washington, the engineers were still writing their report on why the B-25 modifications wouldn’t work. General Kenney sent a one-paragraph reply: “12 of the impossible airplanes just destroyed an entire Japanese convoy. Request immediate production.”

Pappy Gunn was sent to California to show North American Aviation how to build them. The result was the B-25G, which carried a massive 75mm M4 tank cannon in its nose.

One shell from this “flying tank” could punch a hole through a destroyer’s hull. When Pappy test-flew the prototype, the recoil of the 75mm gun was so violent the entire airframe shuddered and slowed by 10 mph. But for Pappy, it was perfect. By the end of the war, nearly 5,000 “Strafer” variants of the B-25 had been built, sinking 800 ships and killing an estimated 85,000 enemy soldiers.

The Reunion and the Cost of War

Pappy continued to fly multiple combat missions every day, even though as a Special Projects Officer, he didn’t have to. Every flight was a personal quest to reach Manila.

In November 1944, Japanese bombers hit Tacloban Airfield. Pappy was in his tent when the bombs fell, and shrapnel severed an artery in his left leg. The surgeons told him he would never fly again. Pappy told them he wasn’t going anywhere until his family was free.

On February 4, 1945, the Santo Tomas internment camp was liberated. Pappy flew to Manila against medical orders, using a cane to walk. When he found his wife, Polly, she didn’t recognize him. He had lost 40 pounds and his hair had turned completely white. They hadn’t seen each other in three years.

The Final Flight

Pappy Gunn retired as a full Colonel in 1948. He returned to the Philippines and rebuilt Philippine Airlines (PAL), the company he had started before the war. He lived as a legend in Manila, a man who had literally re-engineered the war to save his family.

On October 11, 1957, Pappy was flying a routine trip from Manila to Baguio in a twin-engine Beechcraft. He flew into a massive storm cell over the Cordillera Mountains. The turbulence was severe, and the aircraft was driven into a ridge. Everyone on board was killed instantly.

He died one week before his 58th birthday. The Philippine government gave him a state funeral attended by 6,000 people.

Legacy of the Maverick

Paul “Pappy” Gunn changed the face of aerial warfare forever. Before him, bombers were high-altitude tools of precision. Because of his “impossible” tinkered planes, the concept of the Gunship was born.

The AC-130 used in Vietnam and the A-10 Warthog used today are the direct descendants of a man who welded salvaged guns onto a bomber’s nose in a Brisbane dirt lot. He proved that military doctrine is no match for a mechanic with a torque wrench and a reason to fight.

Today, in the National Museum of the Pacific War in Texas, there is a yellowed piece of paper. It is Pappy Gunn’s original hand-drawn sketch of a gun mount. It has no computer modeling and no formal engineering stamps—just the pencil marks of a man who did the impossible because he wanted to go home.

Note: Some content was generated using AI tools (ChatGPT) and edited by the author for creativity and suitability for historical illustration purposes.