(CNN) -- Some reviewers have called "Saving Private Ryan," Steven Spielberg's World War II film about D-Day and the search for a soldier, one of the greatest war movies.

Military historian Antony Beevor begs to differ.

Not only is it not the greatest war movie, it's not even the best cinematic depiction of D-Day, says Beevor, author of the newly published "D-Day: The Battle for Normandy" (Viking).

He admires the famed Omaha Beach opening -- "Probably the most realistic battle sequence ever filmed," he said -- but described the rest of "Saving Private Ryan" as "ghastly."

"It's sort of a 'Dirty Dozen' cliche of the worst form," he said.

He has expanded on the criticism in a lecture. "Spielberg's basic story line had great potential. It shows the tension between patriotic and therefore collective loyalty, and the struggle of the individual for survival: those mutually contradictory pressures, which in many ways lie at the heart of war," Beevor observed in the talk.

If any filmmakers wish to take on D-Day again, Beevor's book provides enough material for a dozen screenplays. Making use of first-person accounts stored in the National Archives, as well as a wealth of other material, Beevor depicts in painstaking detail not only the D-Day landings by American, British, Canadian and Free French forces, but also the subsequent battle for the whole of Normandy that proved pivotal in defeating Nazi Germany.

Beevor says a director would do well to remember that the Allied effort to retake the continent extended well beyond that single day of June 6, 1944.

"D-Day, although an iconic moment, was not actually the end of it. Films like 'The Longest Day' and 'Saving Private Ryan' almost give the impression that D-Day was 'it' and then the next thing people know about was the liberation of Paris," he said. "But in fact it was the fighting in Normandy which was far worse. Casualties on D-Day were far lighter than expected -- [military leaders] had expected 10,000 dead and only 3,000 died.