Historian Stephen Ambrose acknowledged over the weekend that sentences and phrases in his new book, "The Wild Blue," were copied from a work by another historian.

Ambrose was accused of plagiarism by Fred Barnes, executive editor of the Weekly Standard, in a column in the magazine's Jan. 14 issue. Barnes charged that Ambrose borrowed passages from "The Wings of Morning" by historian Thomas Childers, published in 1995. Ambrose footnotes Childers in the sections in question but does not acknowledge quoting directly from the book, Barnes said.

Both books are about World War II bomber pilots.

In a statement issued Saturday through his publisher, the Simon & Schuster division of Viacom, Ambrose said, "Dr. Childers is correct. I made a mistake for which I am sorry. It will be corrected in future editions of the book."

Childers, a professor at the University of Pennsylvania, told the New York Times for Sunday's editions that "I think it is a classy thing to do, and I appreciate it."

[Yesterday, Forbes.com reported that this was apparently not the first instance of Ambrose borrowing from another work without proper attribution, and that passages in the historian's 1975 book "Crazy Horse and Custer" use phrasing contained in Jay Monaghan's 1959 biography of cavalry officer Gen. George Armstrong Custer.]

Ambrose, a professor emeritus at the University of New Orleans, is the author of more than 25 books. One of them, "Band of Brothers," was made into a television miniseries.