On the Cordoba front during the Spanish Civil War, a Loyalist fighter is killed in action in September 1936.
It's a rare picture that encompasses an era; even the most justly famous photographs seldom manage the feat. Eisenstaedt's "V-J Day in Times Square," for instance, perfectly illustrated the rapturous mood of a nation — and much of the world — at the end of the Second World War, but no one would argue that the image somehow captured the five-year war itself. Bill Eppridge's haunting picture of Robert Kennedy's assassination in a Los Angeles hotel kitchen in June 1968 distilled the darkest, most murderous currents of the Age of Aquarius, but no one says of that one photograph: "That was the Sixties."
So, yes, it's phenomenally rare for a single photo to evoke both a discrete moment, and an epoch. But that is exactly what Robert Capa's now-iconic "Falling Soldier" manages to do; there, in one frame, in a picture made at the very moment a Loyalist fighter in Spain is shot and killed, one encounters a distillation of the Fascist violence — and the brutally extinguished Republican sense of hope for a new, free, egalitarian society — that ultimately came to define the Spanish Civil War.
Before Capa's falling soldier became Capa's "Falling Soldier," however — that is, before his picture acquired the patina of reverence, controversy (many people, after all, still believe the scene was staged) and downright myth that have accrued through the years — the photograph was, in fact, just that: a photograph in a magazine. Period.
Here, seven decades after the end of the Spanish Civil War, when Generalissimo Francisco Franco's Nationalists conquered Madrid after a three-year siege, LIFE.com commemorates Capa's photograph — not as an iconic visual document, but as a single picture, published three-quarters of a century ago on page 19 of a weekly magazine that, at the time, had not yet celebrated its first year in print.
After Capa's photo appeared in LIFE, Franco went on to rule Spain for four decades — a dictator who overthrew a legitimate, elected government and not only survived, but thrived in the face of international complacency. Capa covered four more wars after Spain and died, killed by a landmine, camera in hand, in Southeast Asia in 1954.
Today, "Falling Soldier" is regarded as one of the 20th century's indispensable photographs.