Walking past the heavy wooden doors of Willard Straight Hall that April afternoon in 1969, Ed Whitfield felt relieved. For 36 hours he and other members of the Afro-American Society had occupied Cornell University’s student union, and now, with the tense standoff over, the lanky sophomore was leading his fellow protesters out into the cool Ithaca air.

In his left hand, he gripped notes he had taken during the negotiations with administrators to end the occupation; in his right, a loaded rifle, a 7.65-millimeter Argentine Mauser.

As he and other armed students left the building, a crowd of students, reporters, and other onlookers seemed stunned.

"Oh my God, look at those goddamned guns," said Steve Starr, a photographer for the Associated Press, who snapped a picture of the dramatic departure, a shot that would win a Pulitzer Prize.

Looking back, Mr. Whitfield, now 66, says he never expected to become a symbol, one that is both celebrated and derided. As the group’s president, he was focused on the safety of the other black students and himself.

"We wanted to make our leaving a public activity for the sake of our own protection," he says. "I wasn’t thinking what the photographs would look like." ...