“There’s a place for anger,” said Mary Ollenburger, a postdoctoral fellow at the University of Maryland who was in the park with the counterprotesters. “But there’s a place for peace, too.”

News reports had anticipated scuffles at the rally between members of the antifa movement, who have encouraged violence against people they see as fascist, and the Proud Boys, which admits only men and has been involved in street fights.

But for much of the day, the groups had little interaction, in part because of the scores of police officers among them. A few small skirmishes broke out when antifa members tried unsuccessfully to pierce a line of officers after a brief march through downtown Washington. By early Saturday evening, the police said there had been no arrests or reports of injuries.

At the rally, speakers including the far-right activists Laura Loomer, Milo Yiannopoulos and Gavin McInnes, the founder of the Proud Boys, railed against what they said were deliberate efforts by social media giants like Twitter and Facebook to silence their messages online. (While tech companies have struggled with policing their platforms, there is scant evidence that bans are based on ideology.)