At some point, demonstrators plopped down side-by-side against a desk. Several TwitPics and photos on Facebook show the scene, including of the protesters holding up a sign that read, "Don't talk to the cops."
More photos of the protest were posted online, including one that showed a demonstrator holding a large cloth sign that read "Outing the truth is not a crime! Free Bradley Manning." Another man held a cardboard sign with the question, "Obama, why are you prosecuting whistleblowers?"
Thurman told CNN that the pro-Manning movement is gaining momentum. "We think it's outrageous that he's been in jail for more than 800 days," he said.
Since its founding in 2010, the nonprofit Bradley Manning Support Network, based in northern California, has organized rallies across the country for Manning. The group has a strong social media presence on Twitter found at #vets4brad, #bradlymanning and #freebrad. Manning's public Facebook page is usually active.
The network has raised money to pay for Manning's private attorney and experienced court martial counsel David Coombs. The lawyer has kept a blog for more than a year detailing developments in Manning's case, often posting full documents online.
Coombs has filed numerous motions over the past year including asking that charges against Manning be dropped or combined -- motions that have taken time to be addressed by the prosecution and heard at Fort Meade, Maryland, where all pre-trial proceedings have occurred. Coombs has often struck out. Several motions were denied in April.
Just last week, Coombs filed another motion alleging that Manning had been held in the "harshest conditions possible" which constituted "unlawful pretrial punishment." That will no doubt take weeks to be heard.
"That's what is taking so long, and dragging this case out," said Michael Waddington, a criminal defense attorney who has tried at least 150 military hearings and dozens of court martial trials.
Waddington is not involved in Manning's case.
"The defense has tremendous control over whether Manning gets a speedy trial -- or at least a trial that happens before a client spends 800 or more days in jail," he said. "I have never heard of a case lasting 800 days. That doesn't happen."
Most court martial cases -- from date of charges filed to actual trial -- take between 60 to 180 days, he said.
"I wonder if the pro-Manning protesters and the politics of Manning's case are calling the shots here," Waddington said. "Is this about a man or is this about a cause?"
Thurman says it's both. So does protester Lorraine Reitman. She works for the Electronic Frontier Foundation, a donor-funded nonprofit that works to protect freedom on the Web. She was at Thursday's protest, though not in her capacity with the organization.
"I was protesting on my own because Bradley represents something I believe very strongly in. We want his lawyer to make as many attempts to free Bradley as possible," she said. "It's really about not letting the government dictate or frighten people into not doing and saying as they please or limiting information online."
Pro-Manning supporters are amping up their movement ahead of the November election.
On September 6, the final day of the National Democratic Convention, they are planning to rally at Obama campaign headquarters across the country.
"We have supporters in every major city who are participating," Thurman said. "I know we'll have a strong turn out. Bradley should never think that people have forgotten about him."