Since movies based on true life stories often are less than memorable, my expectations here were minimal. However, after viewing this film (finally!), I was very impressed. This story is very well done, with minimal obvious Hollywood embellishments. (No, I've not read the underlying book, of the same title, but now I'd like to.)
In the big scheme of World War II, the events depicted here would have been forgotten except that the central heroic figure, John F. Kennedy, would later become U.S. President. For those of us who lived through the Kennedy years, this portrait of JFK in his 20's is quite consistent with the JFK we later saw when he became nationally prominent and subsequently president. (If "Private Ryan" deserves a movie, then JFK and his shipmates are surely no less entitled.)
The story begins when JFK arrives in the Pacific and is given command of a PT ("Patrol Torpedo") boat. PT boats were fast wooden craft with a crew of 12 and carried four torpedos and some small-bore guns, capable of quickly getting in and out while operating in shallow waters and doing various odd jobs on short notice. Without a lucky torpedo shot, any one boat was not going to be noticed by history.
PT 109 operated into an area of Pacific waters and small islands mainly controlled by the Japanese. One of Kennedy's first missions was to provide covering fire onto shore and extricate some stranded Americans. The boat remained under enemy fire until the rescue was complete, notwithstanding casualties both to crew and those rescued.
On PT 109's final mission, during darkness and limited visibility (radar was not yet on most PT boats), a Japanese destroyer, perhaps unwittingly, slices through PT 109, half of which sinks while the other half capsizes, but not before JFK and surviving crew members make an arduous swim to shore, taking along their wounded---and shoes. Aerial reconnaissance later sights the wreckage and reports "no survivors."
How the PT 109 crew is finally saved results partly from good luck and partly from daring, ingenuity, exhausting swims, and a refusal to give up. Yes, this is also a feel-good movie!
(The movie also acknowledges the part played and risks taken by "coast watchers," isolated individuals who infiltrated islands in Japanese-controlled areas, maintained lookouts from high ground, and radioed back critical information on enemy movements.)
