From the Wiki article about the film:
(Tyrone Power's character in the film was based upon) US Navy Ensign Iliff "Rich" Richardson ( , who) was the executive officer of PT-34. After it was sunk by the Japanese, Richardson and a dozen fellow Americans attempted to sail a native outrigger to Australia, but the boat was sunk in a storm. He eventually joined the Philippine guerrilla forces, setting up a radio network to keep the various bands in touch with each other and Allied forces in Australia. After the liberation of the Philippines, Richardson dictated his memoirs to war correspondent Ira Wolfert, who published them in 1945 as An American Guerrilla in the Philippines. The book became a Book-of-the-Month Club selection and was published in condensed form in the March 1945 issue of Readers Digest.