It is a little unusual for an author of boys' books to engage himself in the argument of a moral proposition any stronger than, say, one concerned with sportsmanship as exemplified in the homilies of the late Grantland Rice, or the salutory effects of telling the truth. But John R. Tunis, who is obviously a highly moral man and one equally troubled by the rising tide of brutality in the world, has attempted something more [in "His Enemy, His Friend"]: an examination of conscience arising out of an incident in World War II.
On the whole, he has brought it off, even though he has had to depend here and there on the conjunction of a couple of outrageous coincidences. Young people are not so apt to question outrageous coincidences as they are doubtful moral propositions, and so "His Enemy, His Friend," a frankly hortatory novel, is apt to do some good. (p. 44)
[The] moral imperatives are satisfied; judgments are made; punishment (possibly divine) is meted out, and the consciences of all men of good will ultimately are satisfied—not without small dollops of irony and pity. (p. 46)
Gilbert Millstein, in The New York Times Book Review (© 1967 by The New York Times Company; reprinted by permission), October 29, 1967.