That's Giants second baseman Tito Fuentes, bat seemingly at the ready. If you watch film of the incident, you'll see that Fuentes plays no role in the fight. He never swings the bat, and in fact it gets plucked out of his hand as other players swarm the field. But he lends the photo a sinister air, as if he and Marichal are ganging up on the stricken Roseboro.

Fuentes, who would enjoy a long career as a bat-flipping showman, was 21 at the time. He'd debuted just a few days earlier, part of an influx of Latino players to which Sports Illustrated dedicated a remarkably ham-fisted story in its Aug. 9 issue. (The Giants had a number of Latino ballplayers: Marichal, Fuentes, Matty and Jesús Alou, and Orlando Cepeda.) "Caribbeans in general have the reputation for being temperamental, and the ballplayers are no exception,"Robert H. Boyle wrote, adding that because of his prideful bearing, "a Latin must be handled more tactfully than his American teammates. The Latin shows a tendency to take criticism, however well intentioned, as a personal affront." He also wrote that "Latins sometimes play with a reckless individuality. Indeed it is the individuality in baseball that they like."

The magazine would be echoed after the incident by columnists like Bob Broeg of the St. Louis Post-Dispatch, who wrote,"These young Caribbean hot bloods absolutely must be taught restraint."

Esteemed photographer Neil Leifer was not supposed to be at Candlestick that afternoon because he had already shot the first three games of the series. But he convinced his assignment editor at Sports Illustrated, George Bloodgood, to allow him to stay over so he could concentrate on shooting Koufax and Marichal using color film.

He set up behind home plate, between the backstop and the first row of seats, in a narrow walkway that was primarily used for television cameras. Thus, he was perfectly positioned to shoot Marichal's Game of Thrones moment.

Leifer, it should be noted, has made a habit of being in the right place at the right time to capture indelible moments in sports history. He snapped Ali standing over Liston in 1965 as well as Alan Ameche's touchdown in the gloaming in 1958.

The Marichal-Roseboro fight happened "so fast," Leifer told me recently, that he had "no idea" if he'd gotten the shot. All he knew was, he was on the 36 th frame of a 36-picture roll of film.

Yes, film: Remember that? "The two things you worried about in those days were focus and exposure—two things nobody worries about today," he said, referring to the advent of digital photography. "I wasn't too worried about the exposure—it was pretty basic because it was a sunny day—but the focus is never a sure thing. I was using a 180-millimeter lens, and I was probably about 80 feet from home plate. The only thing I knew was, mine was the only picture taken at field level. There was no one else down there."

Leifer hand-carried the film back to New York that night. When the magazine's editors saw what he had, Leifer recalled, they changed the layout to make his photo the lead. His composition turned out to be excellent. The bodies and bats in the foreground and the stands in the background converge to frame Roseboro's falling body. Your eye is drawn to him as, arms extended, he crumbles to the grass as in a sacrifice.

The photograph appeared in the Aug. 30, 1965, edition of SI, accompanied by the text: "'Giants' pitcher Juan Marichal, swinging his bat like a henchman's ax, had opened a two-inch gash and raised a swelling the size of a cantaloupe on the left side of Roseboro's head.'"

Like Roseboro, Marichal had things on his mind beyond baseball. He'd spent that whole summer worried sick about the safety of his family and his homeland as the Dominican Republic fractured into a violent civil war. A wealthy landowner with connections through his in-laws to the barbarous ruling Trujillo family, Marichal backed the conservative cause that would eventually regain the presidency in the form of Joaquín Balaguer. Earlier that year, President Lyndon Johnson, fearing a "second Cuba" was in the offing, had sent U.S. forces to the D.R. in an attempt to assert order in the country. "I really don't think Juan should have been playing at all," Willie Mays would later tell The New York Times. "He was pretty strung out, full of fear and anger, and holding it inside."

Marichal received the balance of the blame for the fight. He was suspended for eight playing dates—two starts, essentially—and fined $1,750. Roseboro went so far as to sue Marichal, eventually settling out of court for $7,500. The Dodgers wound up winning the '65 National League pennant by two games over the Giants.

It would be years before Roseboro admitted his own role in touching off the brawl. "It was intentional all right," he said in his autobiography, Glory Days with the Dodgers, and Other Days with Others (written with Bill Libby) in 1978, referring to his ear-grazing throw. "I meant for him to feel it." He'd been steeling himself for a fight, too. "I was so mad I'd made up my mind that if he protested, I was going after him. He protested, so I started out of my crouch. … I went to hit him with a punch, and he hit me with his bat."

Which brings us back to Leifer's photograph, a perfect shot that in a way was too perfect, too articulate, too neatly resonant with the major themes of the day. It showed, or seemed to show, the martyrdom of Johnny Roseboro at a time when Civil Rights advocates were being pummeled by firehoses, German shepherds, and, yes, baseball bats. It showed, or seemed to show, the embodiment of the prevailing stereotype of the "hot-tempered" Latino ballplayer, even though Marichal was anything but hot-tempered.

Great photos tell their own stories, occasionally at the expense of the events being depicted. You think of Leifer's other famous photograph from that year, the one of Muhammad Ali exulting over the stricken Sonny Liston. Through the prism of Ali's greatness, it's seen as a portrait of dominance, such that it blots out the squalid and hinky circumstances of the fight and the knockout itself. Leifer captured Marichal's disproportionate response in such a way that few people remember or even care about the provocation.

Roseboro and Marichal would eventually strike up a friendship. When Marichal's Hall of Fame candidacy ran aground on sportswriters' lingering memories of the fight, Roseboro began to stump for his old nemesis. Upon election in 1983, Marichal phoned up Roseboro to tell him the news.

"I'm going to Cooperstown," he said, as recounted in The Fight of Their Lives. "Thank you. Thank you."

Then the two men cried together.

Related: Doping, Cheating, And Insta-Celebrity: The Story Behind The First Great Sports Action Photograph, Taken In 1908

David Davis is the author of Showdown at Shepherd's Bush: The 1908 Olympic Marathon and the Three Runners Who Launched a Sporting Craze (St. Martin's).