John Morris, a photography editor who shepherded Robert Capa’s indelible images of the D-Day landing in 1944 into print at Life magazine and who later selected two shocking images from the Vietnam War for the front page of The New York Times, helping to turn public opinion against U.S. involvement in the conflict, died July 28 at a Paris hospital. He was 100.

His death was confirmed by a friend, Robert Pledge, the president of Contact Press Images photo agency. The cause was not disclosed.

Beginning at Life magazine in the 1930s and later as executive editor of the Magnum photo agency, Morris supervised such acclaimed photographers as Capa, Henri Cartier-Bresson, Alfred Eisenstaedt and W. Eugene Smith.

Morris was not a photographer himself — except for a few weeks in France in 1944 — but his editorial vision was instrumental in defining the craft and aims of modern photojournalism.

“A picture has to say something, has to have an idea,” he told the photography magazine Black & White in 2014. “From my standpoint, it has to have passion, it has to have human feeling. It also should be well composed, because that’s how the idea comes through. A photographer has to have a head, a heart and an eye.”

One photojournalist who possessed all three qualities was the Hungarian-born Capa, who gained renown during the Spanish Civil War in the 1930s and was working for Life during World War II. Morris was Life’s London-based photo editor, and he was nominally Capa’s boss.

On June 6, 1944, Capa was aboard a transport ship in the first wave of the Allied D-Day assault on Normandy’s Omaha Beach. Wading chest-deep through water and holding his camera above his head as bullets struck all around him, Capa shot the first images of the initial phase of the invasion.

He turned his back toward the German forces firing at him and U.S. troops to capture the face of a young soldier crawling through the water toward the shore. After 90 minutes, Capa boarded a medical transport boat and helped care for wounded soldiers on the return trip to Britain.

His film reached Morris at Life’s London office on the night of June 7. Capa had hastily scrawled a note: “John, all of the action is in the four rolls of 35-millimeter.”

Morris had less than 12 hours to develop the film, annotate the images and secure the approval of Allied censors. To meet Life’s deadline, the photographs had to be in the hands of a courier no later than 9 a.m. the next day, June 8.

Morris shouted at a photo assistant to hurry. In the process of drying the film, the assistant closed the doors of a closet-like space in the darkroom, overheating the emulsion on the film.

“They’re ruined! Ruined! Capa’s films are all ruined!” the assistant said, running to Morris.

“I held up the four rolls, one at a time,” Morris wrote in a 1998 memoir, “Get the Picture.”

“Three were hopeless; nothing to see. But on the fourth roll there were eleven frames with distinct images. They were probably representative of the entire 35-millimeter take, but their grainy imperfection … contributed to making them among the most dramatic battlefield photos ever taken.”

Morris had several sets of prints made and rushed to the censorship office, which examined the photos for several hours before approving them for release.

“I left the ministry at about 8:45 and drove like a maniac through the scattered morning traffic, down the little side streets, reaching the edge of Grosvenor Square at 8:59,” Morris wrote. “I ran the last fifty yards and found the courier … about to padlock his sack. ‘Hold it!’ I shouted, and he did.”

The courier took the photos to an airplane, which flew to an airfield in Scotland, where the photos would be put on a larger plane bound for the United States.

Capa’s pictures were published in the next issue of Life. Blurred, shaken and practically echoing with bursting artillery shells and the shouts of dying soldiers, they showed the tumult of battle with heart-stopping intimacy.

“Their very crudeness gives a feeling of the struggle itself,” Morris said in 2004.

Six weeks later, using a borrowed camera, Morris went to Normandy himself, joining Capa and other Life photographers — and eventually novelist Ernest Hemingway — as they accompanied Allied forces toward Paris as it was liberated from Nazi control. His images were published as a book in France in 2014.

For 70 years, Morris blamed himself for losing three rolls of Capa’s images from Omaha Beach. Only in the past two years, as photographers and historians examined development processes and the nature of the film used by Capa, did a new consensus emerge. Most experts now believe there were never any usable images beyond the original “magnificent 11,” as they are sometimes called. The prevailing belief is that Capa was under such intense fire that he had little chance to shoot other images or that his camera may have malfunctioned.

“I used to take the blame for the loss of Capa’s D-Day film,” Morris said in 2014. “In recent years I’ve learned to say that I’m the one who saved the 11 frames.”

John Godfrey Morris was born Dec. 7, 1916, in Maple Shade, New Jersey, and grew up in Chicago. His father, who was born in 1869, founded a book publishing company and later worked for a Chicago-based college that provided extension courses, or what is now called distance learning.

At the University of Chicago, Morris helped launch a student publication modeled on Life, which was first published in 1936. He was the picture editor.

After graduating in 1938, he found a job in the mailroom of Time-Life publications before becoming Life’s Hollywood correspondent and then London picture editor. He later worked for Ladies’ Home Journal and as the top editor of Magnum, the agency started by Capa and other photographers.

In 1954, he sent Capa on an assignment to Vietnam (then Indochina), where Capa stepped on a landmine and was killed. Several other photographers who worked for Morris also died in the line of duty.

Morris worked for The Washington Post in the 1960s and, from 1967 to 1973, was the picture editor at the Times. In 1968, he insisted that a photo by Eddie Adams of the Associated Press, showing a South Vietnamese police official in the act of executing a Viet Cong prisoner with a shot to the head, be run on the front page of the Times.

Four years later, Morris selected another photo, this time by Nick Ut, showing a naked, screaming Vietnamese girl fleeing a napalm attack. Both pictures won the Pulitzer Prize.

“I have always believed in showing how ugly war is,” Morris told the Times in 2016, “and I have encouraged newspapers to take a realistic view of war.”

Morris’ first wife, the former Mary Adele Crosby, died in 1964. His second wife, the former Marjorie Smith, died in 1981. His third wife, photographer Tana Hoban, died in 2006. Two of his children predeceased him.

Survivors include his companion, Patricia Trocme of Paris; two children from his first marriage; two children from his second marriage; and four grandchildren.

Morris moved to Paris in 1983 and, for six years, was a correspondent and editor for National Geographic. He also headed the Democrats Abroad organization for many years. He completed a 600-page book about his life shortly before his death.

He often traveled to photography workshops, describing his approach to photojournalism and recalling his work with Capa and others.

“I am not a photographer,” Morris told the Times last year. “They did the great work; I just put it in the magazine or newspaper.”