WASHINGTON — A year after the race-fueled violence in Charlottesville, Va., a small group of white nationalists marched through downtown Washington on Sunday on their way to a rally in front of the White House.
It was over almost as soon as it began.
The white supremacists were met along their march route and at the rally site by thousands of counterdemonstrators denouncing racism and white supremacy. The white nationalists, who numbered about two dozen, stayed in Lafayette Square, a park just north of the White House, for a short time and left before 6 p.m.
They had been scheduled to hold a two-hour rally in the square beginning at 5:30. A spokesman for the National Park Service confirmed that the white nationalists had ended their event by that time.
Before they made their exit, the white nationalists were separated from the counterprotesters by metal fences and dozens of law enforcement officers guarding against any outbreaks of violence.
After marching from a neighborhood just west of the White House, the handful of supremacists settled in a pocket of Lafayette Square, tucked underneath trees. Many of them carried American flags, and several wore President Trump’s “Make America Great Again” campaign hats.
The group’s organizer, Jason Kessler, stood on a platform with a microphone, addressing attendees who arrived before the event was scheduled to begin. He blamed a harsh law enforcement response after last year’s Charlottesville rally for his group’s meager showing.
“There were a lot of people who were at last year’s rally who are very scared this year,” he said. “They felt like last year they came to express their point of view. They were attacked. And when they fought back, they were overly prosecuted.”
Counterprotesters in Lafayette Square stood against fencing, shouting and booing in the direction of the white supremacists.
Even as rain began to fall and lightning lit the sky, protesters bearing signs and shirts deploring racism and anti-Semitism remained in Lafayette Square, chanting across rows of police officers, about a half dozen of whom stood guard atop horses.
Anjali Madan Wells, a middle school teacher from suburban Montgomery County, Md., said it was “common sense” for her to come out and protest against the white supremacists.
“The idea that people were gathering in my city to spread a message of intolerance,” she said, adding that “I talk to my students about standing up for what is right.”
In Charlottesville, organizers and participants from last August’s counterdemonstrations there massed in Booker T. Washington Park, just north of the University of Virginia, and a mile from the area downtown where a 32-year-old woman was killed by a neo-Nazi.
Dozens of State Police officers formed a barricade that blocked protesters from moving outside a checkpoint. With no sign of white supremacists there, tensions were confined to interactions between the left-leaning protesters and law enforcement.
As a steady rain set in in the early evening, police officers began breaking down barricades and reopening streets, apparently convinced that the threat of a serious disturbance had waned.
On Saturday, President Trump issued a general call for unity, denouncing “all types of racism,” but not specifically condemning white supremacism.
“Riots in Charlottesville a year ago resulted in senseless death and division,” he wrote on Twitter on Saturday morning. “We must come together as a nation. I condemn all types of racism and acts of violence. Peace to ALL Americans!”
Mr. Trump’s words were reminiscent of his reluctance a year ago after the deadly Charlottesville rally to single out white nationalists, instead blaming “both sides” for the violence, and appearing to draw a moral equivalence between hate groups and counterprotests.
The rally in Washington on Sunday, called Unite the Right II, was scheduled to take over Lafayette Square for two hours in the evening. The Unite the Right group planned to have up to 400 people at the rally, according to the permit it received from the National Park Service, though the group was considerably smaller.
The Park Service, which permits around 750 First Amendment demonstrations annually in the national capital region, granted one last week to Mr. Kessler. “In anyone’s recollection, there has never been a First Amendment permit that’s been denied,” said Mike Litterst, a Park Service spokesman. “There wasn’t much discussion or question of whether or not it would be issued.”
Last year in Charlottesville, neo-Nazis, Ku Klux Klansmen and other members of hate groups marched through the University of Virginia campus shouting anti-Semitic slogans, then fought with counterprotesters in the city streets. A man who espoused neo-Nazi views is accused of driving his vehicle into the counterdemonstators, killing a 32-year-old woman, Heather D. Heyer.
On Sunday afternoon, Susan Bro, Ms. Heyer’s mother, was greeted in downtown Charlottesville by a steady stream of people wanting to hug her.
“I dreaded today,” she said. “I felt the heaviest weight in my heart last night. I got here and all the sirens were freaking me out. And then a calm settled over me.”
Nearby, protesters skirmished with police officers, and at least four arrests had been made.
The chance of spontaneous mayhem led to weeks of planning between Washington’s law enforcement agencies to guard the marches leading to the rally and the rally itself, as well as to deal with any confrontations that followed it in the streets of Washington.
Sgt. James Dingeldein of the Park Police said his agency, the city’s police and the Park Service had met with Mr. Kessler and leaders of counterprotest groups to explain to them what is permissible on the grounds of the park. The Park Service issued a detailed set of limits and prohibitions on items that could be brought in, banning some of the items that were wielded in Charlottesville.
“If there is potential for violence, it will be dealt with quickly,” Sergeant Dingeldein said.
Federal officials expressed concern that violence could spill into other parts of Washington. Sergeant Dingeldein said the police agencies had riot control teams ready.
James Murray, an assistant director in the Secret Service’s Office of Protective Operations, warned in a letter on Monday to the Park Service that it was possible that tension between groups could lead to the same kind of violence that occurred in Portland, Ore., last weekend, where a right-wing rally turned violent after, the police said, a group began throwing rocks and bottles at officers.
Mr. Murray wrote that some of the same counterprotesters who seized downtown streets at the presidential inauguration in January 2017 were also interested in Sunday’s demonstrations, and were “known to have engaged in violent and destructive activity.” Members of the sometimes violent movement known as antifa were expected to be among the counterprotesters on Sunday.
Muriel E. Bowser, the Washington mayor, activated the city’s emergency operations center on Thursday. At a news conference that day, she said Unite the Right participants were an anomaly among visitors to Washington.
“Very few of our visitors share the views that will be expressed in Lafayette Square this weekend,” she said.
Hawes Spencer and Michael Wines contributed reporting from Charlottesville, Va., and Catie Edmondson from Washington.