TRIANGLE, Va. – Wearing T-shirts and carrying signs bearing the smiling image of Army Pfc. Bradley Manning, hundreds of people rallied Sunday outside the base where he’s being detained on charges of providing classified data to WikiLeaks.

About 35 people were arrested by police in riot gear after they refused to vacate an intersection in front of the entrance to Marine Corps Base Quantico. The rally was held along with more than two dozen others around the world to protest Manning’s detention in Quantico’s brig.

Manning is confined alone in his cell for all but one hour a day. Each night, he is stripped naked and given a suicide-proof smock to wear to bed. His attorney has called the treatment degrading, and Amnesty International says it may violate his human rights.

David House, a friend who has visited Manning about 15 times since September, told the crowd that Manning appreciated their support.

President Obama and military officials contend that Manning is being held under appropriate conditions given the seriousness of the charges against him. He faces nearly two dozen charges, including aiding the enemy, a crime that can bring the death penalty or life in prison.

Earlier this month, chief State Department spokesman P.J. Crowley resigned after criticizing the handling of Manning’s detention as “ridiculous, counterproductive and stupid.” Some demonstrators carried signs praising Crowley’s comments.

Daniel Ellsberg, who leaked the Pentagon Papers in 1971, said that solitary confinement is “a form of torture, and as such, it’s illegal internationally and domestically.”

“It’s happening right here to an American soldier in an American brig,” Ellsberg said. He was one of the protesters arrested Sunday amid chants of “Free Bradley Manning.”

Short scuffles ensued as dozens of officers tried to push away the protesters, some of whom were seated on the pavement. Many sat beneath a yellow banner that read: “Caution: Whistleblower Torture Zone.”

Prince William County police said in a statement late Sunday that about 35 people were taken into custody and charged with unlawful assembly and careless interference with traffic. One protester was also charged with assault and battery of an officer.

Manning, a former intelligence analyst and self-styled “hactivist,” is accused of leaking a raft of Iraq and Afghanistan war logs, more than 250,000 confidential State Department cables and a military video of an attack on unarmed men in Iraq.

Ellsberg, a former military analyst who revealed the Pentagon’s secret history of the Vietnam war, said the WikiLeaks cables played a role in sparking the protests that overturned authoritarian regimes in Tunisia and Egypt. He said that if Manning is responsible for the leaks, he’s a hero.

“He had the courage and the conscience to carry out his oath to the Constitution,” Ellsberg said.