Vietnam marked the 50th anniversary of the end of what it calls the American War on Wednesday with a boisterous parade in Ho Chi Minh City featuring soldiers, dancers and speeches celebrating what the country’s communist leader called “a triumph of justice.”

The event brought tens if not hundreds of thousands, according to state media, including many who camped out overnight for the morning’s festivities.

“The atmosphere was very special,” said Nguyen Thi Song Anh, 18, who joined some 12th-grade classmates on a crowded sidewalk near the Opera House. “It was important for me to feel part of this country — and part of this history.”

The scenes of celebration, with a sea of red and yellow representing the flag of Vietnam in front of high-end French and American retailers, pointed to just how distant the final day of this country’s grueling war has become.

Ho Chi Minh City, also still known as Saigon, is now a vibrant metropolis of 9 million people, where skyscrapers shadow the handful of buildings with wartime history and the streets are filled with locally made electric vehicles and young people snapping selfies for Instagram.

On most days, people will tell you the war is irrelevant, too old for concern, except perhaps as a source of gritty stories that drive the young to be grateful for what they have.

But April 30 is different.

Every year, Vietnam honors the dead and recounts how the underdogs of the North definitively defeated the French, the Americans and ultimately South Vietnam.

On Wednesday, To Lam, the top leader of the Communist Party of Vietnam, struck many of the usual chords in a speech before international visitors, which did not include the U.S. ambassador.

But the U.S. Consul General, Susan Burns, was there — a softening of an earlier directive from Washington barring senior diplomats from anniversary events.

Mr. Lam described the conflict as a struggle for national independence and a resistance movement against French colonialism and U.S. aggression. He celebrated “the liberation of the South,” which Washington has generally referred to as “the fall of Saigon.”

Vietnam also included troops from China in Wednesday’s parade for the first time, providing public recognition of Beijing’s assistance during the war. However it was not a huge surprise: A video of Chinese troops at a rehearsal singing the popular patriotic song, “As If Uncle Ho Were With Us on the Day of Great Victory” had already been shared widely on social media.

Still, there were also hints of a more conciliatory approach to past enemies. Even as Vietnam grits its teeth in negotiations with the White House over proposed tariffs set (and postponed) at 46 percent, Mr. Lam noted that 2025 is also when the U.S. and Vietnam celebrate 30 years of diplomatic ties.

Reaffirming an essay he published Sunday, acknowledging a need for greater reconciliation between North and South, he also spoke about “respecting differences.”

“All Vietnamese are sons and daughters of this country,” he said. “All are entitled to live, to work, to pursue happiness and love.”

Ms. Song Anh, the 12th-grader, like many others on the parade route, found the message compelling. Her grandfathers had fought for the North, but she said it was time to “overcome our biases.”

“We are all Vietnamese,” she said. “We all carry a sense of pride.”

On Wednesday, it was on full display. Billboards juxtaposed Ho Chi Minh’s gaze with images of new bridges, connecting past struggles to modern development. Families sang patriotic songs. The young and hip snapped photos of helicopters flying over Independence Palace, the seat of the South’s government, which northern troops seized on April 30, 1975.

Asked if there was anything they would change, a few parade-goers spoke about the need to eliminate corruption, to create an economy that served all more equally.

But many also pointed with admiration to new buildings that would have been unimaginable in the 1970s and ’80s, when the war-wrecked economy was on its knees.

“It’s so emotional, to see all the development and changes happening in Vietnam,” said Tran Quang Duc, 67, who had traveled from the province that Ho Chi Minh was from and wore his military uniform on Wednesday.

“I don’t think anyone would want to fight Vietnam now,” he added, noting that he fought the Chinese in the war that broke out in 1979. “We’re strong and confident.”

We met beside the Rex hotel, where the U.S. military used to hold its briefings, claiming the war was being won. Reporters called them the “five o’clock follies.”

A statue of Ho Chi Minh now stands nearby. Vu Thi Ninh Thuy, 42, gathered there after the parade to take pictures with a few friends. She said she had come out early that morning because the 50th anniversary was a singular event.

“I wanted to be part of it,” she said. “I wanted to feel what it was like to live in historic times.”

Tung Ngo contributed reporting.