The Man With Many Names — Richard Oliver Collin

The mysterious protagonist is known only as the Adviser - an American intelligence officer who has assumed so many false identities that he has lost touch with his own. He arrives in Oman, a desolate and remote country lying between Arabia's Empty Quarter and the Indian Ocean, at the end of a long, bitter guerrilla war; he is haunted by thoughts of a woman named Ellen, about whom there are the darkest of secrets.
In the course of one turbulent day, the Adviser survives more than a man should endure in a lifetime. His companions are Arab soldiers, a charismatic British Sergeant Major named Woodward, and a memorable lunatic called Napalm.
A strange, quick friendship develops between the tormented American and the gallant Englishman when they rescue a beautiful Arab child named Bint. By the end of the day, all the threads of the Adviser's life come together, and Ellen's full story is revealed.