For Let Freedom Ring: Stanley Tretick’s Iconic Images of the March on Washington, biographer Kitty Kelley edited and arranged Tretick’s never-before-published images from August 28, 1963.

How did you find these wonderful photographs?

When I was putting together Capturing Camelot, which came out last year, and looking at Stanley’s work with the Kennedys, I found over 200 photographs of the March. This year is the 50th anniversary of the March, which was the crescendo of the Civil Rights Movement. More than 300,000 people came to petition Congress to pass the Civil Rights Bill.

Were you surprised by all of the elements that had to come together?

I was fascinated to find out that Washington had closed down. The government closed, restaurants closed. They brought in the National Guard and opened the hospitals, expecting violence. But there was not one violent incident.

How did you decide on the book’s format?

I put Stanley’s photos together with an essay, then brought in the historical context, participants, and singled out the 10 speakers. Until the March, there were six leaders of the Civil Rights Movement—all African-American men based in Southern churches. But Martin Luther King, Jr. insisted on including white church leaders, Christians, Jews, teachers, unions. They started out with little flyers in Nashville and Jackson and Greensboro, but this became a national, then international, movement. People came from Australia, from England. Hollywood chartered jets to bring their folks to Washington. All these people came to bear witness and dressed in their Sunday best.

Did the flyers say how people should dress?

They passed out instructions about how to behave and they did ask for white shirts and black pants. The men wore hats, and so did the women. It’s hard to imagine 300,000 people assembling in the nation’s capital in August today without incident. But the people were absolutely infused with the spirit of nonviolence.

Why weren’t these photographs published earlier?

Stanley was given special access because he was a photographer for Look Magazine. But Look took six weeks to publish, so they never ran anything on the March because they were too far behind. It was wonderful to put the history of the day together, to start out with the Kennedys being against the March, show what a glorious day it turned out to be, and end with Stanley’s photo of Lyndon Johnson and his speech on civil rights and the passage of the bill that followed.