The marchers set off from the Yard shortly after 1 p.m., squeezing through Holyoke Gate and pouring into Mass. Ave.

“What do we want?” someone shouts over a megaphone.

“Regime change,” the crowd chants in unison.

“Where do we want it?”

“Here!”

Cambridge Police officers on motorcycles guide the marchers into the left lane of the street as they headed east toward the MIT, their next stop.

Mr. Bartley, the white-haired owner of the Harvard Sqare landmark Bartley’s Burger Cottage, leans in the entrance to his restaurant, watching the crowds as they pass.

At the intersection of Mass. Ave. and Bow St., two march participants stop to ask Divinity School student Kyle M. Hall whether he will manage the long walk ahead. He hurt his ankle while running last week and is hopping up the street with crutches, carrying a backpack and two water bottles on his back.

“Yeah,” he says. “I’m going to make it there even if I kill myself.”

Hall says his religious beliefs made participation in the march necessary in spite of his injury.

“My Christian faith compels me to be here,” he explains. He wants to help effect the peace of Christ, he says.

A new chant overtakes the crowd. “What do we want?” a leader calls.

“Peace!” the marchers answer.

“When do we want it?”

“Now!”