Editor's note: This is an excerpt from John Blake's 2004 book "Children of the Movement." The PBS documentary "Freedom Riders," which airs Monday at 9 p.m. ET, features James Zwerg, now 71. Blake interviewed him in 2003. This report contains objectionable language.
(CNN) -- The mob was already waiting for James Zwerg by the time the Greyhound bus eased into the station in Montgomery, Alabama.
Looking out the window, Zwerg could see men gripping baseball bats, chains and clubs. They had sealed off the streets leading to the bus station and chased away news photographers. They didn't want anyone to witness what they were about to do.
Zwerg accepted his worst fear: He was going to die today.
Only the night before, Zwerg had prayed for the strength to not strike back in anger. He was among the 18 white and black college students from Nashville who had decided to take the bus trip through the segregated South in 1961. They called themselves Freedom Riders. Their goal was to desegregate public transportation.
Zwerg had not planned to go, but the night before, some students had asked him to join them. To summon his courage, Zwerg stayed up late, reading Psalm 27, the scripture that the students had picked to read during a group prayer before their trip.
"The Lord is my light and my salvation, of whom shall I fear?" the Psalm began. But there was another passage at the end that touched Zwerg in a place the other students didn't know about: "Though my mother and father forsake me, the Lord will receive me."
Zwerg's parents had forsaken him for joining the civil rights movement. That same night, he had written a letter that was to be handed to them in case he was killed. It explained his decision to join the Freedom Riders.
Zwerg called his mother to tell her where he was going.
"Don't go. Don't go," she said. "You can't do this to your father."
"I have no choice. I have to," he said.
"You killed your father," his mother replied. Then she hung up.
The Greyhound bus doors hissed open. Zwerg had volunteered to go first. The mob swarmed him as he stepped off the bus, yelling, "Nigger lover! Nigger lover!"
Then, as the mob grabbed him, Zwerg closed his eyes and bowed his head to pray. "The Lord is my light and salvation, of whom shall I fear ... "
The mob dragged him away.
Zwerg tells the story behind the photo
James Zwerg, right, with John Lewis after the mob attacked them. Zwerg passed out soon after the photo was taken.
What happened next would furnish the civil rights movement with one of its most unforgettable images. Photographers eventually broke through and snapped pictures of what the mob had done to Zwerg and another Freedom Rider, John Lewis. The pictures were broadcast around the world.
Zwerg looked like a bloody scarecrow. His eyes were blackened and his suit was splattered with blood. After he was hospitalized, a news crew filmed him in his hospital bed. Barely able to speak, Zwerg declared that violence wouldn't stop him or any of his friends. The Freedom Rides would go on.
Zwerg became one of the movement's first heroes. Although his physical wounds healed, the emotional ones took longer. He was wracked with guilt and depression after the beating. He drank too much, contemplated suicide, and finally had to seek therapy.
He was drawn to the Freedom Rides after he was assigned a black roommate while attending Beloit College in Wisconsin. He grew to admire his roommate and was shocked to see how the young man was treated by whites when they went out in public together. So he volunteered to be an exchange student at Fisk University in Nashville, an all-black college, for one semester. He wanted to know how it felt to be a minority.
Zwerg had gone to a city that had become a launching pad for the civil rights movement. He was swept up in the group of Nashville college students who were initiating sit-ins and Freedom Rides. He was awed by their commitment.
Zwerg's parents were unaware of the changes taking place in their son. They were enraged when they opened their local newspaper the day after he was attacked and saw the now-famous picture of their battered son on the front page.
Zwerg later tried to explain to them that what he did as a Freedom Rider was an outgrowth of what they had taught him, but they remained angry. "These are the two people who instilled my Christian beliefs, my ethics," he says, "and now they were saying, this time when I lived my faith to the fullest, they didn't accept it."
Zwerg would try to talk to his father about his decision, but they could never finish the conversation.