Dwight Eisenhower credited a bankrupt Louisiana lumber dealer with winning the war for the Allies. This episode follows Andrew Higgins from the bayous of the 1920s, where his Eureka boat with its tunnel stern and spoonbill bow could slide onto mud banks and back off again, serving trappers, oil drillers, and Prohibition rum runners. When the Depression and the repeal of Prohibition wiped out his business, the Marine Corps’ looming amphibious problem gave him a second chance.

We trace his fight with the Navy’s Bureau of Construction and Repair, the Fleet exercises of 1938 and 1939 where his boat outperformed the Navy’s own designs, the fatal flaw of the solid bow on the early LCPL, and the 1941 photograph of a Japanese Daihatsu ramp boat that inspired the fix. Higgins built three ramped prototypes at his own expense, tested them on Lake Pontchartrain with his own employees, and the result was the plywood LCVP, more than 23,000 of which carried troops onto beaches from Normandy to Iwo Jima.

• How the tunnel stern protected the propeller in shallow, stump-filled water
• Why the Navy bureaucracy resisted a proven design from an uncredentialed outsider
• The LCPL’s solid bow and why troops had to climb over the sides under fire
• Why the LCVP was built of plywood instead of steel and relied on speed, not armor
• Surviving Higgins boats emerging from Lake Mead, Shasta Lake, an Alaskan boatyard, and a Normandy farmyard