In 2002, Ambrose was accused of plagiarizing several passages in his book The Wild Blue by Sally Richardson and others. Fred Barnes in The Weekly Standard reported that Ambrose had taken passages from Wings of Morning: The Story of the Last American Bomber Shot Down over Germany in World War II by Thomas Childers, a history professor at the University of Pennsylvania. Ambrose had footnoted sources, but had not enclosed in quotation marks, numerous passages from Childers' book. Ambrose and his publisher, Simon and Schuster, released an apology as a result.
Ambrose asserted that only a few sentences in all his numerous books were the work of other authors. He offered this defense:
I tell stories. I don't discuss my documents. I discuss the story. It almost gets to the point where, how much is the reader going to take? I am not writing a Ph.D. dissertation.
I wish I had put the quotation marks in, but I didn't. I am not out there stealing other people's writings. If I am writing up a passage and it is a story I went to tell and this story fits and a part of it is from other people's writing, I just type it up that way and put it in a footnote. I just want to know where the hell it came from.
A Forbes investigation of his work found cases of plagiarism involving passages in at least six books, with a similar pattern going all the way back to his doctoral thesis. The History News Network lists seven of Ambrose's works--The Wild Blue, Undaunted Courage, Nothing Like It In the World, Nixon: Ruin and Recovery, Citizen Soldiers, The Supreme Commander, and Crazy Horse and Custer--that copied twelve authors.
Factual errors and disputed characterizations
Veterans of troop carrier units who transported paratroopers in the American airborne landings in Normandy have severely criticized Ambrose for portraying them as unqualified and cowardly in several of his works, including Band of Brothers and D-Day. Among the numerous errors he asserts in an open letter posted on the War Chronicle website, Randy Hils notes that Ambrose did not interview a single troop carrier pilot. This becomes highly relevant in light of Ambrose's assertion that the pilots sped up while the paratroopers were trying to jump. Hils hypothesizes that if Ambrose's only sources were inexpert witnesses whose only indication of airspeed were the sound of the engines, the maneuver of using the propellers as an airbrake would have sounded like power being applied.
Two Ambrose accounts in D-Day of alleged cowardice by British coxswains have also been challenged as inaccurate. One, in which Sgt. Willard Northfleet is portrayed as drawing his gun on a coxswain when he tried to offload the men 400 yards from shore, is corroborated by Sgt. John Slaughter (who was on the boat) in a C-SPAN video recording veterans' D-Day experiences. It was disputed by Kevan Elsby, however, on the basis of a contemporary debriefing which stated that "Four hundred yards frm shore the British coxain insisted that he could take the craft no farther so the men must swin for it. He started to lower the ramp but Platoon Sgt. Willard R. Norfleet blocked the mechanism and insisted that the boat was going farther." The other, in which Capt. Ettore Zappacosta was portrayed as drawing his gun on a coxswain to make him go in when he protested he could not see the landmarks, was challenged by Pvt. Bob Sales as untrue. Both Ambrose and Sales assert that Sales was the only survivor from that landing craft.
A number of journal reviews sharply criticized the research and fact checking of Nothing Like It in the World: The Men Who Built the Transcontinental Railroad, 1863-1869, Ambrose's non-academic popular history published in August, 2000, about the construction of the Pacific Railroad between Council Bluffs, Iowa and the San Francisco Bay at Alameda. Reviewer Walter Nugent observed that it contained "annoying slips" such as mislabeled maps, inaccurate dates, geographical errors, and misidentified word origins, while Don L. Hofsommer agreed that the book "confuses facts" and that "The research might best be characterized as 'once over lightly'."
A front page article published in The Sacramento (CA) Bee on January 1, 2001, entitled "Area Historians Rail Against Inaccuracies in Book," listed more than sixty instances identified as "significant errors, misstatements, and made-up quotes" in the book documented in a December, 2000, fact checking paper compiled by three long time Western railroad researchers who specialize in the history of the Pacific Railroad, while on January 11, 2001, Washington Post columnist Lloyd Grove reported in his column, The Reliable Source, that a co-worker had found a "serious historical error" in the same book that "a chastened Ambrose" promised to correct in future editions.
The Eisenhower controversy
Two of Ambrose's statements regarding his interaction with President Eisenhower have been proven false: that Eisenhower initiated the biography project and that he spent "hundreds of hours" with the former president in preparation of the manuscript.
Ambrose often claimed that he was solicited by Eisenhower after the former president had read and admired Ambrose's life of General Henry Halleck. But Tim Rives, Deputy Director of the Eisenhower Presidential Center, says it was Ambrose who contacted Eisenhower and suggested the project, as shown by a letter from Ambrose found in the Dwight D. Eisenhower Presidential Library and Museum.
After Eisenhower's death in 1969, Ambrose made repeated claims to have had a unique and extraordinarily close relationship with him over the final five years of the former President's life. In an extensive 1998 interview, for instance, Ambrose stated that he spent "a lot of time with Ike, really a lot, hundreds and hundreds of hours" interviewing Eisenhower on a wide range of subjects, and that he had been with him "on a daily basis for a couple years" before his death "doing interviews and talking about his life."
Rives has stated, however, that a number of the interview dates Ambrose cites in his 1970 book, The Supreme Commander, cannot be reconciled with Eisenhower's personal schedule. The former president's diary and telephone show that the pair met only three times, for a total of less than five hours. Later, Ambrose was less specific when citing dates of interviews with Eisenhower.