Beneath a vast night sky and billowing red clouds, award-winning actress and singer Jennifer Hudson delivered a moment of harmonic splendor Tuesday night as she rang up the start of the national anthem, her soaring voice inspiring the first of many thunderous roars of applause along the Mall.

With the U.S. Capitol as its glowing, iconic backdrop, the Concert for Valor began as a somber and stirring tribute to generations of American veterans who sacrificed their lives and well-being through the years.

But the three-hour concert also was a rollicking showcase for a full panoply of American sound — from Rihanna’s passionate R&B to Metallica’s raging heavy metal; from Eminem’s sneering rap to Bruce Springsteen’s soothing acoustic strains. There was alt-rock from the Black Keys and country from Carrie Underwood.

“How you feel out there? The whole world is watching!” actor Jamie Foxx said as the show started at 7 p.m., leading the crowd in chants of “USA! USA!”

Foxx took a moment to set the tone, mocking people who are overly concerned about whether they own the right Mercedes and other gilded possessions. “I ran into a guy in my hotel who didn’t have a hand,” Foxx said. “Let’s stop complaining.”

As the nation’s capital, Washington is well schooled in the sights and sounds of pageantry, with hordes arriving each year for the annual July 4 celebration and every four years for the presidential inauguration.

But the Concert for Valor, which HBO broadcast live, was something different, a sometimes incongruous mix of full-throated patriotism and Hollywood-style performance with videotaped cameos by President Obama and Reese Witherspoon.

The hours leading up to the concert were a kind of endurance test for those eager to get early entree to a show that also featured Dave Grohl, whose acoustic rendition of his tune “My Hero” turned into a massive, flag-waving singalong.

IPods, board games, changes of shoes, hair spray, salami sandwiches and anti-bacterial hand wipes — all were among the necessities spectators lugged through security checkpoints as rifle-toting officers loomed close by.

At certain spots and at certain moments, the smell of burning marijuana was as obvious as the camouflage and red, white and blue that many spectators incorporated into their outfits.

Michael Frye, 23, a National Guard specialist who volunteered to work security, spent hours watching the crowds from a minivan on 12th Street. If the work was tedious, it gave him a chance to participate in the pageantry and be close enough to hear the Zac Brown band deliver a rousing rendition of “America the Beautiful.”

“I wanted a good memory to have . . . one to call on someday,” Frye said.

Julia Watson came from Cleveland to sell patriotic souvenirs before the Concert for Valor on Tuesday. (Katherine Frey/The Washington Post)

The crowds began arriving more than 12 hours before the concert’s first performance, navigating a maze of closed downtown streets and security with hopes of nabbing close-up views.

Jennifer Ragle, who with her 11-year-old daughters left their home in the Rappahannock County, Va., community of Amissville at 4:30 a.m., ditched her car at a meter near the Capitol, hoping there would be no ticket 15 hours later.

Her biggest complaint was that she couldn’t find one of life’s singular necessities.

“Where’s the bathroom?” she asked as she stood at Seventh Street and Constitution Avenue, waiting in a line to get onto the Mall.

Not a single Porta-Potty was in sight.

As the gates opened at 10 a.m., the early arrivals could be heard bemoaning the distance from their spots in the general-admission section to the stage — more than 100 yards. But Cynthia Graham, 44, who traveled from Beaverdam, Va., in Hanover County, said the best views should be reserved for the veterans.

About 12,000 tickets were set aside for members of the military.

Graham’s son, Sterling, served in the Army for three years, including a year in Afghanistan, and her younger son, Sean, with her at the concert, is planning to enlist.

“I’m fine back here,” Graham said, wearing a faded black Metallica shirt and sitting against the rail that marked the front of the general-admission section. “It’s just not too many venues where you get country and metal at the same place. We decided we were coming weeks ago — as soon as we heard about it.”

It was Rihanna who inspired Tamara Allen, 29, and a group of friends to leave Philadelphia in the dead of night to make it to the Mall by 5 a.m. and be first in line.

“She works hard, so we work hard to support her,” Allen said of the singer.

Once through the gates, concertgoers were herded into one of two security lines. The labyrinth of fencing was made even more complicated by a series of lanes created to allow dozens of wheelchair-using or disabled veterans to travel freely to and from prime seating areas.

“I just can’t believe this crowd, man,” said Forrest Tanner, 56, who was struck in the neck by a bullet in 2009 when his convoy was attacked in Baghdad. He wore an elaborate neck brace and used a walker. “It’s tearing me up. Just to be here, I’m a lot better off than others.”

About noon, the first sound to come from the loudspeakers was an acoustic version of Grohl’s “My Hero.”

Hundreds of fans jumped up from their blankets and whipped out their cellphones to record the Foo Fighters frontman’s signature growl.

Afterward, there was silence again, and kids went back to their naps and older people to the card games many seemed to be occupying themselves with during the hours-long wait for the concert.

Anthony Smith, 58, of the Bronx defined the day as being about freedom, history — and T-shirts. “It’s my day,” said the Vietnam veteran, who got up at 2:30 a.m. to sell concert T-shirts near the Mall. “This is what I do.”

By early afternoon, he had sold 45, about a third of what he hoped to sell by night’s end.

There were no reports of medical emergencies or other major problems at any of the 13 first-aid stations set up along the Mall or the two family reunification stations, a U.S. Park Police spokeswoman said. By mid-afternoon, volunteers at one tent said that all they had done was hand out three packets of sunscreen.

Although the concert didn’t start until nightfall, a slew of major roads were closed early, including most streets south of Pennsylvania Avenue and west of Third Street. The stretch also was blocked off south of the Metro Center and Gallery Place Metro stations, between Seventh and 12th streets.

People hoping to go to the National World War II Memorial ran into their first inconvenience when they discovered their path blocked by temporary metal fencing. Some visitors who had entered the Mall at checkpoints at 12th and 14th streets walked past the Washington Monument almost to the World War II Memorial when they were stopped in their tracks.

“We just walked all that way,” a woman said.

Metro also adjusted its normal service levels because of the concert.

The change made it more complicated for riders trying to reach Arlington National Cemetery. They had to get to the Pentagon, Pentagon City, Crystal City or National Airport stations and take a shuttle train, which ran about every 15 minutes between the airport and the cemetery.

Throughout the morning, though, passenger traffic was light, the shuttle seemed to run as scheduled and many people who were headed to the cemetery — even those who got lost along the way — seemed in no mood to complain. Rather, on a day for remembrance, they seemed calm and reflective.

The Metro hassle?

“It’s worth it,” said Georgia Lenzmeier, 62, a retired guidance counselor from Idaho who was headed to visit the grave of one of her former junior high students, Army Capt. Luke C. Wullenwaber, who was killed in Iraq in 2004.

Aaron C. Davis, Paul Duggan, Dana Hedgpeth, Fredrick Kunkle and Victoria St. Martin contributed to this report.