Gen. David Petraeus is used to controversy surrounding the war in Iraq, but his publicized thoughts on an Army chaplain's book for Soldiers put him squarely in the middle of the ongoing conflict over religious proselytizing in the U.S. military.

The book is "Under Orders: A Spiritual Handbook for Military Personnel," by Army Chaplain (Lt. Col.) William McCoy, and according to Petraeus' published endorsement of the work, "it should be in every rucksack for those times when soldiers need spiritual energy."

But the endorsement - which has spurred a demand by a watchdog group for Petraeus' dismissal and court martial on the grounds of establishing a religious requirement on troops - was a personal view never intended for publication, the book's author now says.

"In the process of securing … comments for recommending the book I believe there was a basic misunderstanding on my part that the comments were publishable," McCoy said in an Aug. 19 email to Military.com. "This was my mistake."

People close to the campaign also floated a wild-card choice, Gen. David H. Petraeus, the top American commander in Iraq. They said it was not beyond the realm of possibility that Mr. McCain would ask him to join the ticket, although General Petraeus has no experience in elective government and has said repeatedly that he is not interested in the vice presidency.

One adviser characterized General Petraeus, who presided over a recent reduction of violence in Iraq, as more of a wish-list candidate for Mr. McCain, who, like the general, long supported sending additional troops to quell the insurgency.