A rally by right-wing demonstrators on the famed Boston Common, planned for this Saturday, failed to register on Marty Walsh’s radar last week.

The Boston mayor knew little about the Boston Free Speech Coalition, the group that defines itself as “a coalition of libertarians, progressives, conservatives, and independents” that seeks to “peaceably engage in open dialogue about the threats to, and importance of, free speech and civil liberties.”

By that definition, it sounds like a tame gathering of First Amendment lovers. But the group -- which has also expressed interest in marching against immigrant sanctuary cities -- invited two white nationalists to address the crowd at its upcoming rally.

After last weekend's "Unite the Right" event in Charlottesville, Va., in which neo-Nazis and white nationalists clashed violently with anti-racism protesters, leaving one counter-protester dead and more than a dozen people injured, Walsh and city leaders are rushing to make preparations that hopefully keep the same sort of violence from happening in Boston.

The Boston free speech rally is part of a coordinated nine-city protest against tech giant Google's decision to fire a software engineer after he circulated a controversial 3,300-word memo against diversity. Other protests are planned for this Saturday in Atlanta, Austin, Los Angeles, New York, Pittsburgh, Seattle, Washington, D.C., and Mountain View, Calif.

After the violence in Charlottesville, Boston's Democratic mayor initially vowed to stop the protest altogether.

“Boston does not welcome you here. Boston does not want you here. Boston rejects your message,” Walsh told media in front of City Hall on Monday, according to the Boston Globe. “We are going to do everything we can that this march does not happen or this demonstration does not happen on Saturday.”

Despite those strong words, the march has been permitted, and Boston is now bracing for both sides to converge on one of the most highly trafficked spots in the city.

The Boston-based Lawyers’ Committee for Civil Rights and Economic Justice called on the city to release its safety plan.

“If these back-to-back rallies are any indication, this threat is metastasizing,” says Ivan Espinoza-Madrigal, executive director of Lawyers’ Committee for Civil Rights and Economic Justice. “The proposed rally should not move forward until Boston has a comprehensive public safety plan. We cannot be the next Charlottesville.”

The Boston Police Department, however, has offered few details about their preparations.

“I am not going to give away our game plan," says Boston Police Commissioner William B. Evans. "We will have barriers; we will have pedal bikes; we will have plenty of assets to keep them at bay."

Walsh and Evans express confidence that the city and state police can keep the opposing sides of the demonstration separate and therefore minimize violence. Charlottesville police had a similar plan, but protesters did not abide by their rules.

The lack of details and the lack of time for the city of Boston to prepare for the rally has drawn further criticism from Espinoza-Madrigal. He wants at least portions of the Boston PD's plan released to allay any fears the public might have. There are also worries that Boston's extensive mass transit network will make it easy for any conflicts that might occur to spread throughout the city.

The Boston Free Speech Coalition claims to have no ties to the white nationalist groups in Charlottesville and said their event will not promote racism and hate. But Boston city leaders worry there may be some overlap between the free speech groups and the white nationalists, and that an event like the one planned for Saturday will attract hate groups to the Boston Common.

At least two of the speakers originally booked for the Boston rally, Gavin McInnes and Augustus Invictus, also spoke in Charlottesville and are regulars at white nationalist events around the country. McInnes was a co-founder of Vice Media and founder of the Proud Boys, an alt-right fraternity. McInnes backed out of the Boston rally, and Invictus was uninvited. However, Joe Biggs, who once worked for Alex Jones’ alt-right website InfoWars and promoted the "Pizzagate" conspiracy, is reportedly planning to attend.

The Charlottesville rally was held in response to that city's plan to remove a statue of Confederate General Robert E. Lee. At least 26 cities across the nation have either removed or have plans to remove Confederate memorials. While most of the memorials are clustered in the South, Confederate monuments have been or are planned to be removed in Los Angeles, San Diego and New York City. Lexington, Ky., Mayor Jim Gray announced on Saturday that two Confederate statues in his city would be taken down and relocated.

Political pressure from progressives and the African-American community to remove the statues has mounted. But in the wake of last weekend's violence in Charlottesville, the memorials have also begun to raise questions about public safety: Do the controversial statues, which have become flashpoints for protest, make cities less safe?

That was the reasoning behind Baltimore Mayor Catherine Pugh's decision to remove four Confederate statues in her city this week. The violence in Charlottesville expedited her plans, she says, and the statues were taken down in the early morning hours on Wednesday. Removing the memorials in Baltimore, says Pugh, squelches protests and decreases the potential for violence that stems from those demonstrations.

"I can say for every city who has a Confederate statue in their city, you don’t want to invite those elements to your city," Pugh says.

Pugh's actions echoed the strategy used earlier this year by New Orleans Mayor Mitch Landrieu. He made a unilateral decision to take down four Confederate memorials in the middle of the night. Landrieu also made national headlines for his speech explaining why he believed the statues needed to come down.

"These monuments," said Landrieu, "purposefully celebrate a fictional, sanitized Confederacy; ignoring the death, ignoring the enslavement, and the terror that it actually stood for."