Why PT boat crews stripped guns from crashed P-39 Airacobras during WW2 — and destroyed over 800 Japanese vessels. This World War 2 story reveals how a desperate field modification became factory-standard naval armament.
October 19, 1942. Lieutenant Robert Lynch, commanding PT-48, watched Japanese barges carrying troops off Cape Esperance. His torpedoes couldn’t hit them – minimum depth 10 feet, barge draft 5 feet. His .50-caliber guns bounced off their armor. At Henderson Field three miles away, wrecked P-39 Airacobras sat with their 37mm automatic cannons intact. Lynch and his crew cut the guns from crashed fighters and welded crude mounts on their boat’s deck. Every Navy regulation said this was unauthorized modification. Bureau of Ordnance called it dangerous improvisation.
They were all wrong.
What Lynch discovered that night wasn’t about following procedure. It was about solving real tactical problems with available resources in a way that contradicted everything Navy doctrine taught. By the end of the first patrol – Zero Hour off Guadalcanal – Squadron commanders started requesting salvaged cannons for their boats. And Japanese barges started burning.
This technique spread unofficially through Motor Torpedo Boat Squadrons 2, 3, 5, and 6, crew to crew, destroying 800+ Japanese vessels before official channels even responded. The improvised mount design from Henderson Field’s machine shop would prove more influential than anyone expected. Japanese commanders called PT boats “devil boats” because of these guns.
Credit to : WW2 Records