Well before dawn on August 2, 1943, 26-year-old Lt. John F. Kennedy and his crew on PT 109 were astonished to see a massive shape appear out of the moonless night in the Solomon Islands. Only seconds later that form became the speeding Japanese destroyer Amagiri, and before the Americans could avoid it, the ship rammed the much smaller torpedo boat, igniting a fireball of high-octane gasoline. The impact killed two Americans and left 11 others, including Kennedy, to swim for their lives.

The story of how Kennedy's men survived—and were later rescued from a small island—quickly became a legend of American history. In the 1960 presidential campaign the tale of JFK's heroism in the South Pacific helped persuade Americans to vote for the young charismatic leader.

One key to the events of that fateful night, however, seemed forever lost. PT 109 was believed to have split into two pieces, the aft starboard section sinking immediately, the bow section floating on for another half day or more before it disappeared. Having found many lost ships in my career, I was confident we could locate her remains. So earlier this year, nearly 60 years after she'd gone down, we went looking for PT 109.

Jack Kennedy's early life didn't necessarily point to naval heroism. He'd grown up on the water in places like Hyannis Port, Massachusetts, and had learned to sail at an early age. But like young Teddy Roosevelt, he'd suffered frequent illnesses. He might have chosen an easier path; fresh out of college he'd published his first book, Why England Slept, getting good reviews. His father, Joseph P. Kennedy, the former ambassador to Great Britain, was wealthy and politically connected and could have opened almost any door for him.

But once war seemed likely, Kennedy wanted to fight. In April 1943 he took up his command at Tulaghi off Guadalcanal in the Solomon Islands. His assigned boat, PT 109, was already battered by war and tropical climate, but he and his green crew brought her back into fighting shape.

Although the PT boats were fast and exciting, some considered them risky because their hulls bore no armor and were loaded with explosive aviation fuel. Only four of the 15 boats sent out on August 1, 1943, had radar. That afternoon U.S. code breakers had reported that the Japanese would try to resupply their forces in the area through a "Tokyo Express"—a convoy of fast and dangerous destroyers sweeping south from the huge Japanese base at Rabaul on New Britain. PT 109 and the other torpedo boats were sent out from their base in Rendova Harbour to harass and interfere with these critical resupply shipments in Blackett Strait off Kolombangara.

About midnight the Express passed near the American PT boats, a number of which fired torpedoes at the speeding convoy. Undeterred, the Japanese continued to Vila on the southern coast of Kolombangara Island and unloaded more than 70 tons of supplies and hundreds of troops in lightning time before the order was given to race back to Rabaul.

Around 2:30 a.m. Kennedy's lookout saw a ship appear out of the darkness, illuminated by the phosphorescence of its bow wave. JFK and his men had only seconds to react. Kennedy wanted to fire his torpedoes, but he and the crew couldn't get the boat to respond quickly enough. Before they could swing into position, the larger vessel was upon them.

Based on everything we'd learned from accounts of the collision between PT 109 and the Amagiri, we mapped out a 5-by-7-mile grid of Blackett Strait as our primary search area. Our initial strategy was to use our sonar sled Echo to look for the "slice," or aft section of the boat, that had sunk instantly. Although it was small and made of wood, it probably still contained engine parts and other metal objects that would show up brightly on sonar

Within three days we'd marked hundreds of potential targets, including about a dozen that looked particularly promising. We sent our unmanned video vehicles, Argus and Little Hercules, down on Tuesday May 21, but one target after another turned out to be rock formations or junk. We were losing valuable time, and there were just too many targets.

The next day we changed our strategy and began looking for a profile to correspond with the bow section. We took a big risk here, because previous theories had speculated that the hull had drifted off into Ferguson Passage, outside our search area. But one of the Australian coastwatchers, Lt. Arthur Reginald Evans, reported seeing wreckage still drifting south in Blackett Strait on the morning of August 2—after which he reported seeing nothing for two days. And sure enough, on May 22, zeroing in on a hull-shaped profile 1,200 feet below the surface in an area with no other targets, we peered through our TV camera at what appeared to be torpedoes or torpedo tubes.

On Thursday May 23 we were joined by Dick Keresey, former commander of PT 105 who had also been on patrol in Blackett Strait the night PT 109 went down, and Max Kennedy, son of JFK's brother Robert. We reran our tapes from the bottom. Although we couldn't read definitive markings on the wreckage, it looked like the real thing. We double-checked our records, making sure that no other PT boat had been lost in the area except for PT109. Weeks later our hunch was backed up by Navy scholars who closely examined our video images.

Before we left the Solomons, Max Kennedy presented gifts and a family donation to Biuku Gasa and Eroni Kumana, the two island scouts who had carried out messages from JFK and his crew that led to their rescue. Now proud great-grandfathers, the two men wept from the emotion of the moment, and the rest of us felt incredibly lucky as well. Despite long odds, our expedition had added a missing chapter to the history of an American icon.

Subscribe to National Geographic magazine.