Or so the technician had told him, Mr. Morris said, and he related that account for 70 years or so.

Recalling the episode, he told NPR in 2002: “I said, ‘I can’t believe it.’ So I ran to look at them with him, and I held up the rolls one at a time. And the first three were just soup. You couldn’t see anything. But on the fourth roll of film, the last one, there were 11 images that were discernible. And those pictures saved us, and those were the pictures that have come to symbolize D-Day ever since.”

But recently, persuaded by newer theories that have since emerged, he came to believe that a darkroom error was not the reason there were so few Capa frames. He told James Estrin of The Times last December that he believed that Mr. Capa had been so rattled during the withering fire at Omaha Beach that he exposed only 11.

Mr. Morris went to Normandy himself within weeks of the invasion to see the Western Front for himself and better understand the photos he had been editing in London. Allowed to walk ashore at Normandy in July 1944, he spent a month in the combat zone accompanying photographers, including Mr. Capa, for Life and The Associated Press. In Normandy, he and Mr. Capa narrowly avoided being wounded when they came under fire from a German platoon.

Mr. Morris left Life’s London bureau at the end of the war and, after a brief stint heading the magazine’s Paris bureau, returned to New York and became the picture editor of Ladies’ Home Journal.

It was an unlikely home for the kind of photojournalism he had championed, but in 1948 he persuaded the magazine’s editors to print photographs of Russia that Mr. Capa had taken on a trip with John Steinbeck, and he later introduced a series of picture essays called “People Are People the World Over.”

By Mr. Morris’s account, the series partly inspired Edward Steichen to curate “The Family of Man,” an exhibition of more than 500 pictures by more than 270 photographers that opened at the Museum of Modern Art in 1955.

His association with Mr. Capa led Mr. Morris to leave Ladies’ Home Journal to become the first executive editor of Magnum, which had been founded by Mr. Capa, Henri Cartier-Bresson, David Seymour and George Rodger in 1947.