In 1948, David Seymour – known as Chim – on assignment for Unicef, returned to a Europe ravaged by war. His task was to photograph children who had lived through the conflict. The devastation he encountered must have resonated deeply with him, for his parents, Polish Jews, had not survived the Holocaust. There is a particular poignancy to his visit to the town of Otwock, just outside Warsaw, where he discovered that a pension once owned by his family now housed a Jewish orphanage, Dom Dziecka. His camera captures the orphans playing on the very site where he too had once played as a child.

It was at another Polish orphanage, this time in Warsaw, where he took one of his most celebrated photographs. Six-year-old Tereszka, asked to draw a house, has produced a furious scribble. The child stands before the blackboard, her wild eyes holding our attention against the backdrop of her troubled, chaotic depiction. A caption informs us that Tereszka survived the war in a concentration camp, where she witnessed unspeakable horrors. But while this history seems to explain the girl’s disturbed expression, Cynthia Young, who curated the 1996 and 2013 exhibitions of Chim’s photographs at the International Center of Photography, has pointed out the caption is almost certainly wrong: We do not know who Tereszka was or where she spent the war; all we have is a disconcerting, dissonant image onto which others have projected their interpretations, influenced perhaps by Chim’s sad postwar odyssey. What is more certain here is the power of a great photograph – not only to move the viewer emotionally but to influence philanthropic action: The Tereszka Children’s Foundation was named for the child in Chim’s iconic photograph.

While Chim left no written account of his trip to postwar Europe, we get a clue to what he felt from the foreward he wrote for his UNESCO book, Children of War. Calling it a “Letter to a Grown-up,” he chose to speak in the voice of a child. “I am not writing to you today out of resentment,” he begins, “although I could easily detest you – indeed I have done so more than once.”

Chim was born Dawid Szymin in 1911 in Warsaw, the son of a publisher of Yiddish and Hebrew books. After completing his schooling in Poland, he studied printing technology in Leipzig before enrolling at the Sorbonne in Paris in 1932. Concerned about dwindling family finances after the Great Depression, Chim found a job with family friend David Rappaport, who owned a picture agency in Paris. Borrowing a camera, he began taking photographs and, with his precocious ability, soon saw his images published. The prints were stamped with the name “CHIM,” a shortened, phonetic version of his surname. It was in Paris in the early 1930s that he met Robert Capa and Henri Cartier-Bresson. In time their friendship and collaborative expertise would significantly influence the world of photojournalism.

In the hotbed of French politics in the 1930s, Chim’s leftist sympathies found a home with his appointment as staff photographer to Regards, a weekly magazine aligned with the socialist alliance the Popular Front. In turn, the political ferment in France provided him with a natural segue to the Spanish Civil War, which began in 1936. Three years later, with the Republican cause lost, he accepted an assignment from Match to photograph Loyalist Spanish refugees fleeing to Mexico on board the S.S. Sinai. From Mexico he made his way to the United States, arriving in September, 1939 – just as the Second World War began in Europe.

At that point Chim’s career as a photographer was put on hold. He was drafted into the U.S. Army and became a naturalized U.S. citizen. It was then that he changed his name to David Robert Seymour, reportedly fearing the Germans would make a connection between the newly minted American and his parents trapped in occupied Poland. It is tempting to think that in his choice of surname the polyglot with an impish sense of humour had resorted to clever wordplay, hitting on a name that spoke to his perceptive eye as a photographer. After a series of military promotions, he returned to France just after D-Day, was discharged from military service in 1945 and began working at Leco, a photograph-processing lab. He picked up his camera again only in 1947, the year he co-founded the photography co-operative Magnum Photos with George Rodger, William Vandivert and his old Parisian friends Capa and Cartier-Bresson.

In 1950, Inge Bondi was hired by Magnum as a secretary and researcher. Like Chim and Capa, she was a refugee, having escaped Germany as a child with the Kindertransport. “Magnum was very small in those days,” she recalls. “It was regarded by the photography world as an elegant club. Capa and Chim especially kept up with the lifestyles of the LIFE photographers, who were very well paid. They wore Brooks Brothers grey suits, silk shirts made to measure in Rome and mainly black ties. Chim once told a younger photographer: ‘You don’t go to see an editor dressed like a plumber!’”

Behind Chim’s debonair persona, however, could be found a different set of emotions. Writing to his sister Eileen, who had also escaped from Europe and was now living in New York, he confided, “My life was always broken in pieces and kind of disjointed due to circumstances, and I am trying hard to make sense of it.” In his personal search for meaning, he was naturally drawn to the new state of Israel. “It was like coming home again,” he wrote to Eileen in 1948. “It was like picking up the living threads of my life, for which I had been searching in vain on the heaps of rubble and ash in the ruins of Warsaw.” Although he visited the fledgling nation often, photographing life in a country struggling to absorb the survivors of the Holocaust, he never settled there. To Eileen, her brother “was basically an unhappy man, torn in himself and lonely despite the glamour of his career and the many friends he made wherever his assignments took him.” Cartier-Bresson was attuned to this as well, confiding his impression to Bondi that “Chim was not the same after the war.”

Chim, as his Unicef work showed, had a great affinity for children, but he never married or had any of his own. He poured his energy into his work, taking photographic assignments from major European and American publications that saw him travel widely through Italy, Greece and Israel. His interests were eclectic, ranging from a series devoted to the Vatican and Catholic rituals to a portfolio of celebrities that included Ingrid Bergman, Peggy Guggenheim, Sophia Loren, Audrey Hepburn, Ava Gardner, Arturo Toscanini and Bernard Berenson, among others.

Between projects, he focused his managerial skills on developing Magnum, the core of which had shrunk after the early departure of Rodger and Vandivert. “Magnum was a great substitute for a lost family,” recalls Bondi. “I thrived on the intimacy it offered in those early days.” Capa’s untimely death in 1954 while covering the war in Indochina came as a double blow to Chim, personally and professionally. The older Chim had been mentor and teacher to Capa, and their brotherly relationship also had a caring fatherly aspect to it. The two had shared much during tumultuous times. Both had fled Europe, anglicized their Jewish names, fashioned new identities and careers and, driven by a passion to change the relationship between photographers and the agencies that employed them, founded the Magnum co-operative. Along the way, both had also acquired a taste for fine living.

Chim and Capa may have shared a tailor and enjoyed good restaurants, but their characters were very different. Chim did not have his friend’s dashing, derring-do approach to life. Bondi recalls him as “sweet, discreet, private, cultured, politically astute.” Chim’s nephew, Ben Shneiderman, deftly captures the essence of these temperamental differences, paraphrasing the famous Capa dictum, “Your pictures are not good enough if you’re not close enough” by tacking on the word “emotionally” to describe his uncle’s philosophy.

Chim was not a war photographer. To be sure, he went to Spain during the civil war and took some combat pictures, but even there he tended to hang back from the action, preferring to photograph political rallies, civilians trying to get by, children at play. So how did it come to pass that this gentle, cultured man met his end in a war zone, 17 years since he had last set foot in one? Once again, he left no written or verbal record that directly answers this question, but pointers may be gleaned from what he told one of his girlfriends, Judy Friedberg. Here we see the legacy of the Shoa cast a long, fateful shadow. October of 1956 saw the outbreak of two major conflicts – the Hungarian Revolution and the Suez Crisis. Chim chose to cover the latter for Newsweek.

“You asked what made him do it?” Friedberg wrote to Bondi. “He was a newsman, this was news. Moreover his beloved Israel was involved. But even more basic than that was a disjointed series of remarks and letters, which make me think Chim simply had to cover this action since he had deliberately removed himself from events in Central Europe. … [His] last words to me were to get my bags packed and head east, to Budapest and Warsaw. ‘Go,’ he said, ‘where I should go but can’t bring myself to do it yet.’ Emotionally he felt, and repeated this several times, that he was not yet ready to go back.”

Chim arrived in Port Said and, for reasons unknown but against character, he teamed up with the all-action Paris Match journalist Jean Roy. “A cowboy to end all cowboys” was how Ben Bradlee, the Washington Post editor, recalled him. Roy, whose CV included parachuting into Normandy with the Allied invasion in 1944, had purloined an Egyptian army jeep captured by the French to which he had affixed the plate BAL 00-24, the telephone number of Paris Match. On Nov. 10, 1956, four days after an armistice had been agreed, the two journalists set off to cover an exchange of wounded prisoners, the gung-ho Roy at the wheel and Chim, who had never learned to drive, in the passenger seat. Attempting to cross from the Anglo-French to the Egyptian side, their jeep was fired upon by Egyptian forces. Chim died instantly; the injured Roy survived only to be executed by an Egyptian officer soon thereafter.

Shneiderman, nine years old at the time, recalls his mother hearing of her brother’s death on the radio and collapsing in grief. To Chim’s friends, their sadness was mixed with bemusement at the manner in which he had died. “Unluckily, he met up with a madman, Jean Roy,” lamented Friedberg. “Somehow I was sure that wise, little Chim would know better than break the first precept of war photography: Never be first down an empty road. Sadly, he either didn’t or didn’t care.”

Chim left behind an enduring photographic legacy as a founder of Magnum – and with a body of work imbued with a deep humanity. He had an uncanny ability to set his subjects at ease, including most memorably young children, giving him access to their lives and emotions at that very moment he pressed the shutter.

This facility to connect with his subjects – perhaps innate, possibly honed by his own past and unsettled personal circumstances – allowed him to capture the human spirit in a way that holds the viewer captive.

In trying to understand this complex, gifted and enigmatic man, the final word can be left fittingly to his eloquent and perceptive friend and colleague, Cartier-Bresson. “Chim picked up his camera the way a doctor takes his stethoscope out of his bag, applying his diagnosis to the condition of the heart. His own was vulnerable.”

With thanks to Ben Shneiderman, Carole Naggar, Inge Bondi, Cynthia Young, Susan Meiselas, Ryan Buckley and James Fox. The letter from Judy Friedberg to Inge Bondi was obtained courtesy of the Magnum Foundation Archive, MF011-001, Box 1, CHIM Death.