What is the author's tone in Five Years to Freedom: The True Story of a Vietnam POW by James N. Rowe?

The tone of the story is one of hope despite the odds though this is marred by the feeling that some of those captured may not survive and the deaths described. The setting is real as are the events which makes the story disturbing to some readers, especially those who have endured similar situations. There are words and phrases peculiar to the setting and time that may be confusing to some readers, though the meanings are generally understood by reading the words into the context of the story.