In the hush of quiet prayers, in a bugler’s strains of taps, in a widow’s vigil at her husband’s grave and a president’s caution not to forget a war that has not ended, the country on Monday remembered its fallen troops.

The grieving and the reverent arrived early at Arlington National Cemetery, some seeking solace beside headstones of white marble in the solemn burial grounds and others gathering to hear President Obama speak on the first Memorial Day of his second term.

It was a day when the toll of American wars was honored in small towns and leafy suburbs and downtown parades across the country, with American flags clutched by the young and the old and waving from houses and civic buildings and grave sites.

Tributes took many forms. Along Constitution Avenue, thousands of people lined up Monday for the National Memorial Day Parade. There were tourists, picnickers, families in matching red, white and blue outfits, Boy Scout troops, and babies in strollers.

In Arlington’s Section 60, where many service members who were killed in Iraq and Afghanistan are buried, the loss and sacrifice seemed acute and at times heart-rending.

President Barack Obama attended Memorial Day services at Arlington National Cemetery on Monday where he gave a speech and laid a wreath at the Tomb of the Unknowns. (Sandi Moynihan/The Washington Post)

There, a 29-year-old widow named Natalie Schmidt laid on a blanket she had placed over the grave of her husband, Staff Sgt. Jonathan P. Schmidt. He had been gone just eight months — shot in Batur village in Afghanistan, five days before their son turned 3.

Schmidt had started her Memorial Day by scrubbing his headstone to an even more brilliant shade of white. The marker was surrounded by flags and flowers and mementos left behind by family members and fellow soldiers.

At the grave site, Schmidt listened to music that evoked memories and passed time “just talking to him.” It was her first Memorial Day without him, she said, but she was glad to be at Arlington. “I cry to pieces when I’m at home,” she said. “It’s very peaceful here.”

Obama mentioned such sacrifice as he took part in a Memorial Day observance at Arlington and continued a tradition among presidents of laying a wreath at the Tomb of the Unknowns.

The president paid respects to Korean War veterans, noting that it was the 60th anniversary of the end of fighting in Korea, but mostly dwelled on continuing sacrifices as more than 60,000 troops remain in Afghanistan. More than 6,700 troops have died in U.S. conflicts over the past decade.

Obama talked about three service members who recently lost their lives in the conflict and a mother’s plea that her child’s service in Afghanistan, now the nation’s longest war, not fade from memory.

“As we go about our daily lives, we must remember that our countrymen are still serving, still fighting, still putting their lives on the line for all of us,” he said.

When the ceremonies ended, Obama stopped at Section 60. Families crowded around the president and his wife, who were joined by Defense Secretary Chuck Hagel.

“Can I give you a hug?” one woman asked Obama.

“Of course you can,” he replied.

He turned to another young woman, who gave her name as Taylor. “Who are you remembering here, Taylor?” Obama asked.

“My brother’s in Afghanistan,” she said.

“Well, we’re so proud of him,” Obama said.

The cemetery brought together others honoring the day’s larger meaning.

Marine Capt. Clarence Loomis, 36, was there with his family to see the grave of Marine Sgt. Maj. Joseph J. Ellis, who died in Iraq in 2007 and, he said, “was one of those guys that made you want to be a better person.”

Patrick Minihan, 40, a Massachusetts teacher who served in the Army, with deployments in Iraq and Afghanistan, was marking his 11th Memorial Day at Arlington. The former staff sergeant had a seat in the amphitheater for the president’s remarks and intended to walk the grounds .

“For me, it’s important to see the faces there to recognize these are not just numbers, but there is a specific human cost,” he said.

Elsewhere, six family members and a friend had pulled up chairs in Section 60 beside the headstone of Sgt. First Class Brenda Arrindell, who was 44 and had been awarded a Bronze Star for service in Iraq when she died unexpectedly in 2011 after physical training exercises.

They had been sitting for hours — praying, reflecting, “thinking about the good times, joking, laughing, crying, all the emotions,” said Lt. Col. Karlotta Richards, a friend.

Not far away, the son and wife of Navy Cmdr. William Thomas Todd, of Springfield recalled the retired 65-year-old officer, who died last summer and who had himself visited Section 60 on several occasions to talk with family members of the fallen.

His granddaughter, Michaela Todd, 8, in from Nebraska, had placed a rose on headstone after headstone in the cemetery, saying again and again: “Sleep in peace.”

Across the river, paradegoers cheered on high school marching bands, service members carrying massive flags, Civil War reenactors, vintage convertibles and celebrities like country singer Trace Adkins and actor Gary Sinise.

Abby Knapp of the Kansas City area was flanked by her parents, relatives and close friends, all of whom have become a support system since her husband, Sgt. Michael J. Knapp, was killed in Afghanistan in May 2012. It was his third tour with the Army.

Several in the group wore T-shirts that read: “Team Mike, KIA Operation Enduring Freedom.”

“Memorial Day has a new meaning for us,” said Knapp, 28, whose family was unfamiliar with the military world before she and Mike married

Knapp is now trying to teach her daughter Kinsley about her father’s dedication. Kinsley, who was 3 months old when her father deployed, is nearly 2 now.

“Every time she sees a guy in uniform, she says, ‘Daddy!’ ” Knapp said. “Kinsley is going to be a strong little girl growing up. She has to be.”

Anne E. Kornblut contributed to this report.